From e735883171d4908c7ad6ecbbf4626422de7506be Mon Sep 17 00:00:00 2001
From: Niran Babalola <niran.babalola@coinbase.com>
Date: Sat, 10 Jan 2026 23:46:52 -0600
Subject: [PATCH] Cache flashblock trie nodes to optimize bundle metering

Add a single-entry cache for flashblock trie nodes to avoid redundant I/O
when metering multiple bundles against the same flashblock state.

Key changes:
- Add FlashblockTrieCache with ensure_cached() for lazy trie computation
- Add FlashblockTrieData containing TrieUpdates and HashedPostState
- Update meter_bundle to accept optional cached_flashblock_trie parameter
- Use TrieInput::prepend_cached() to prepend cached trie for state root
- Add arc-swap and reth-trie-common dependencies

When multiple bundles are metered against the same flashblock, the cache
ensures the flashblock's trie is computed only once. Each bundle's state
root calculation then measures only its own incremental I/O.
---
 Cargo.lock                               | 242 ++++++++++++-----------
 Cargo.toml                               |   1 +
 crates/client/metering/Cargo.toml        |   4 +
 crates/client/metering/src/lib.rs        |   7 +-
 crates/client/metering/src/meter.rs      | 117 ++++++++---
 crates/client/metering/src/metrics.rs    |  24 +++
 crates/client/metering/src/rpc.rs        |  53 +++--
 crates/client/metering/src/trie_cache.rs |  88 +++++++++
 8 files changed, 383 insertions(+), 153 deletions(-)
 create mode 100644 crates/client/metering/src/metrics.rs
 create mode 100644 crates/client/metering/src/trie_cache.rs

diff --git a/Cargo.lock b/Cargo.lock
index ff365f0e..59afbea8 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -88,9 +88,9 @@ checksum = "683d7910e743518b0e34f1186f92494becacb047c7b6bf616c96772180fef923"
 
 [[package]]
 name = "alloy"
-version = "1.4.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "05c97aa0031055a663e364890f2bc15879d6ec38dae9fbeece68fcc82d9cdb81"
+checksum = "cf23ee5a0d40c75ade22bf33f117058461fc30a95e84d48b01c845c28f4ea7c5"
 dependencies = [
  "alloy-consensus",
  "alloy-contract",
@@ -111,9 +111,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-chains"
-version = "0.2.27"
+version = "0.2.25"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "25db5bcdd086f0b1b9610140a12c59b757397be90bd130d8d836fc8da0815a34"
+checksum = "dd208e8a87fbc2ca1a3822dd1ea03b0a7a4a841e6fa70db2c236dd30ae2e7018"
 dependencies = [
  "alloy-primitives 1.5.2",
  "alloy-rlp",
@@ -124,9 +124,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-consensus"
-version = "1.4.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8e30ab0d3e3c32976f67fc1a96179989e45a69594af42003a6663332f9b0bb9d"
+checksum = "41e46a465e50a339a817070ec23f06eb3fc9fbb8af71612868367b875a9d49e3"
 dependencies = [
  "alloy-eips",
  "alloy-primitives 1.5.2",
@@ -152,9 +152,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-consensus-any"
-version = "1.4.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c20736b1f9d927d875d8777ef0c2250d4c57ea828529a9dbfa2c628db57b911e"
+checksum = "07001b1693af794c7526aab400b42e38075f986ef8fef78841e5ebc745473e56"
 dependencies = [
  "alloy-consensus",
  "alloy-eips",
@@ -167,9 +167,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-contract"
-version = "1.4.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "008aba161fce2a0d94956ae09d7d7a09f8fbdf18acbef921809ef126d6cdaf97"
+checksum = "3ef1b07c3ff5bf4fab5b8e6c46190cd40b2f2fd2cd72b5b02527a38125d0bff4"
 dependencies = [
  "alloy-consensus",
  "alloy-dyn-abi",
@@ -277,9 +277,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-eips"
-version = "1.4.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "15b85157b7be31fc4adf6acfefcb0d4308cba5dbd7a8d8e62bcc02ff37d6131a"
+checksum = "707337efeb051ddbaece17a73eaec5150945a5a5541112f4146508248edc2e40"
 dependencies = [
  "alloy-eip2124",
  "alloy-eip2930",
@@ -326,9 +326,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-genesis"
-version = "1.4.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a838301c4e2546c96db1848f18ffe9f722f2fccd9715b83d4bf269a2cf00b5a1"
+checksum = "64ba7afffa225272cf50c62ff04ac574adc7bfa73af2370db556340f26fcff5c"
 dependencies = [
  "alloy-eips",
  "alloy-primitives 1.5.2",
@@ -392,9 +392,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-json-rpc"
-version = "1.4.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "60f045b69b5e80b8944b25afe74ae6b974f3044d84b4a7a113da04745b2524cc"
+checksum = "48562f9b4c4e1514cab54af16feaffc18194a38216bbd0c23004ec4667ad696b"
 dependencies = [
  "alloy-primitives 1.5.2",
  "alloy-sol-types 1.5.2",
@@ -407,9 +407,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-network"
-version = "1.4.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2b314ed5bdc7f449c53853125af2db5ac4d3954a9f4b205e7d694f02fc1932d1"
+checksum = "364a5eaa598437d7a57bcbcb4b7fcb0518e192cf809a19b09b2b5cf73b9ba1cd"
 dependencies = [
  "alloy-consensus",
  "alloy-consensus-any",
@@ -433,9 +433,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-network-primitives"
-version = "1.4.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5e9762ac5cca67b0f6ab614f7f8314942eead1c8eeef61511ea43a6ff048dbe0"
+checksum = "21af5255bd276e528ee625d97033884916e879a1c6edcd5b70a043bd440c0710"
 dependencies = [
  "alloy-consensus",
  "alloy-eips",
@@ -545,9 +545,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-provider"
-version = "1.4.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ea8f7ca47514e7f552aa9f3f141ab17351332c6637e3bf00462d8e7c5f10f51f"
+checksum = "5cc919fe241f9dd28c4c7f7dcff9e66e550c280bafe3545e1019622e1239db38"
 dependencies = [
  "alloy-chains",
  "alloy-consensus",
@@ -574,7 +574,7 @@ dependencies = [
  "either",
  "futures",
  "futures-utils-wasm",
- "lru 0.16.3",
+ "lru 0.13.0",
  "parking_lot",
  "pin-project",
  "reqwest",
@@ -589,9 +589,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-pubsub"
-version = "1.4.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4082778c908aa801a1f9fdc85d758812842ab4b2aaba58e9dbe7626d708ab7e1"
+checksum = "23a0778833917a71a9e0065e0409bfc00cddef55ca962b3453472be38ebe7035"
 dependencies = [
  "alloy-json-rpc",
  "alloy-primitives 1.5.2",
@@ -633,9 +633,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-rpc-client"
-version = "1.4.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "26dd083153d2cb73cce1516f5a3f9c3af74764a2761d901581a355777468bd8f"
+checksum = "2b587e63d8c4af437b0a7830dc12d24cb495e956cc8ecbf93e96d62c9cb55b13"
 dependencies = [
  "alloy-json-rpc",
  "alloy-primitives 1.5.2",
@@ -659,9 +659,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-rpc-types"
-version = "1.4.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8c998214325cfee1fbe61e5abaed3a435f4ca746ac7399b46feb57c364552452"
+checksum = "97b3000edc72a300048cf461df94bfa29fc5d7760ddd88ca7d56ea6fc8b28729"
 dependencies = [
  "alloy-primitives 1.5.2",
  "alloy-rpc-types-engine",
@@ -672,9 +672,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-rpc-types-admin"
-version = "1.4.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "730a38742dc0753f25b8ce7330c2fa88d79f165c5fc2f19f3d35291739c42e83"
+checksum = "ebb98103316e6f4a1ebc6e71328c2d18426cdd79fc999c44afd9f0f4e9f5edd6"
 dependencies = [
  "alloy-genesis",
  "alloy-primitives 1.5.2",
@@ -684,9 +684,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-rpc-types-anvil"
-version = "1.4.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a2b03d65fcf579fbf17d3aac32271f99e2b562be04097436cd6e766b3e06613b"
+checksum = "f1207e852f30297d6918f91df3e76f758fa7b519ea1e49fbd7d961ce796663f9"
 dependencies = [
  "alloy-primitives 1.5.2",
  "alloy-rpc-types-eth",
@@ -696,9 +696,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-rpc-types-any"
-version = "1.4.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4b4a6f49d161ef83354d5ba3c8bc83c8ee464cb90182b215551d5c4b846579be"
+checksum = "6ebc96cf29095c10a183fb7106a097fe12ca8dd46733895582da255407f54b29"
 dependencies = [
  "alloy-consensus-any",
  "alloy-rpc-types-eth",
@@ -707,9 +707,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-rpc-types-beacon"
-version = "1.4.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3b6654644613f33fd2e6f333f4ce8ad0a26f036c0513699d7bc168bba18d412d"
+checksum = "3cea7c1c22628b13b25d31fd63fa5dfa7fac0b0b78f1c89a5068102b653ff65c"
 dependencies = [
  "alloy-eips",
  "alloy-primitives 1.5.2",
@@ -727,9 +727,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-rpc-types-debug"
-version = "1.4.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "467025b916f32645f322a085d0017f2996d0200ac89dd82a4fc2bf0f17b9afa3"
+checksum = "7e1a6b13b6f95b80d3ff770998f81e61811264eb1d18b88dfa11c80180acdc1b"
 dependencies = [
  "alloy-primitives 1.5.2",
  "derive_more",
@@ -739,9 +739,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-rpc-types-engine"
-version = "1.4.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "933aaaace9faa6d7efda89472add89a8bfd15270318c47a2be8bb76192c951e2"
+checksum = "f35af673cc14e89813ab33671d79b6e73fe38788c5f3a8ec3a75476b58225f53"
 dependencies = [
  "alloy-consensus",
  "alloy-eips",
@@ -759,9 +759,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-rpc-types-eth"
-version = "1.4.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "11920b16ab7c86052f990dcb4d25312fb2889faf506c4ee13dc946b450536989"
+checksum = "9cc3f354a5079480acca0a6533d1d3838177a03ea494ef0ae8d1679efea88274"
 dependencies = [
  "alloy-consensus",
  "alloy-consensus-any",
@@ -781,9 +781,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-rpc-types-mev"
-version = "1.4.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1826454c2890af6d642bf052909e0162ad7f261d172e56ef2e936d479960699c"
+checksum = "10fbd905c35f780926ff0c4c2a74d3ce7d50576cb0e9997dc783ac99c6fd7afb"
 dependencies = [
  "alloy-consensus",
  "alloy-eips",
@@ -796,9 +796,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-rpc-types-trace"
-version = "1.4.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "498375e6a13b6edd04422a13d2b1a6187183e5a3aa14c5907b4c566551248bab"
+checksum = "6d782d80221dfaa5a2f8a7bf277370bdec10e4e8119f5a60d2e2b1adb2e806ca"
 dependencies = [
  "alloy-primitives 1.5.2",
  "alloy-rpc-types-eth",
@@ -810,9 +810,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-rpc-types-txpool"
-version = "1.4.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6d9123d321ecd70925646eb2c60b1d9b7a965f860fbd717643e2c20fcf85d48d"
+checksum = "a3076c226bb4365f9c3ac0cd4082ba86208aaa1485cbf664383a90aba7c36b26"
 dependencies = [
  "alloy-primitives 1.5.2",
  "alloy-rpc-types-eth",
@@ -822,9 +822,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-serde"
-version = "1.4.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d1a0d2d5c64881f3723232eaaf6c2d9f4f88b061c63e87194b2db785ff3aa31f"
+checksum = "a438ce4cd49ec4bc213868c1fe94f2fe103d4c3f22f6a42073db974f9c0962da"
 dependencies = [
  "alloy-primitives 1.5.2",
  "arbitrary",
@@ -834,9 +834,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-signer"
-version = "1.4.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5ea4ac9765e5a7582877ca53688e041fe184880fe75f16edf0945b24a319c710"
+checksum = "389372d6ae4d62b88c8dca8238e4f7d0a7727b66029eb8a5516a908a03161450"
 dependencies = [
  "alloy-primitives 1.5.2",
  "async-trait",
@@ -849,9 +849,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-signer-local"
-version = "1.4.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3c9d85b9f7105ab5ce7dae7b0da33cd9d977601a48f759e1c82958978dd1a905"
+checksum = "69c260e78b9c104c444f8a202f283d5e8c6637e6fa52a83f649ad6aaa0b91fd0"
 dependencies = [
  "alloy-consensus",
  "alloy-network",
@@ -1012,9 +1012,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-transport"
-version = "1.4.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4e72f5c4ba505ebead6a71144d72f21a70beadfb2d84e0a560a985491ecb71de"
+checksum = "f01c27edb3c0926919586a231d99e06284f9239da6044b5682033ef781e1cc62"
 dependencies = [
  "alloy-json-rpc",
  "auto_impl",
@@ -1035,9 +1035,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-transport-http"
-version = "1.4.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "400dc298aaabdbd48be05448c4a19eaa38416c446043f3e54561249149269c32"
+checksum = "2cc57657fd3249fc8324cbbc8edbb7d5114af5fbc7c6c32dff944d6b5922f400"
 dependencies = [
  "alloy-json-rpc",
  "alloy-transport",
@@ -1053,9 +1053,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-transport-ipc"
-version = "1.4.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ba22ff961cf99495ee4fdbaf4623f8d5483d408ca2c6e1b1a54ef438ca87f8dd"
+checksum = "92a5a36d4ca1261a29dd1d791cd89c21b71d7465211910e43b0862d1c067a211"
 dependencies = [
  "alloy-json-rpc",
  "alloy-pubsub",
@@ -1073,9 +1073,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-transport-ws"
-version = "1.4.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c38b4472f2bbd96a27f393de9e2f12adca0dc1075fb4d0f7c8f3557c5c600392"
+checksum = "e81effa6a2db6b2152eefb244b4aa6334b1c42819d0eca8d5a91826ec7a9fdba"
 dependencies = [
  "alloy-pubsub",
  "alloy-transport",
@@ -1110,9 +1110,9 @@ dependencies = [
 
 [[package]]
 name = "alloy-tx-macros"
-version = "1.4.0"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e2183706e24173309b0ab0e34d3e53cf3163b71a419803b2b3b0c1fb7ff7a941"
+checksum = "99dac443033e83b14f68fac56e8c27e76421f1253729574197ceccd06598f3ef"
 dependencies = [
  "darling 0.21.3",
  "proc-macro2",
@@ -1624,12 +1624,13 @@ dependencies = [
 
 [[package]]
 name = "async-compression"
-version = "0.4.37"
+version = "0.4.36"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d10e4f991a553474232bc0a31799f6d24b034a84c0971d80d2e2f78b2e576e40"
+checksum = "98ec5f6c2f8bc326c994cb9e241cc257ddaba9afa8555a43cffbb5dd86efaa37"
 dependencies = [
  "compression-codecs",
  "compression-core",
+ "futures-core",
  "pin-project-lite",
  "tokio",
 ]
@@ -2073,11 +2074,14 @@ dependencies = [
  "alloy-genesis",
  "alloy-primitives 1.5.2",
  "alloy-rpc-client",
+ "arc-swap",
  "base-bundles",
  "base-client-node",
  "base-flashblocks",
  "eyre",
  "jsonrpsee",
+ "metrics",
+ "metrics-derive",
  "op-alloy-consensus",
  "rand 0.9.2",
  "reth-db",
@@ -2091,6 +2095,7 @@ dependencies = [
  "reth-provider",
  "reth-revm",
  "reth-transaction-pool",
+ "reth-trie-common",
  "revm-database 9.0.6",
  "serde",
  "tokio",
@@ -2210,9 +2215,9 @@ dependencies = [
 
 [[package]]
 name = "base64ct"
-version = "1.8.3"
+version = "1.8.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2af50177e190e07a26ab74f8b1efbfe2ef87da2116221318cb1c2e82baf7de06"
+checksum = "7d809780667f4410e7c41b07f52439b94d2bdf8528eeedc287fa38d3b7f95d82"
 
 [[package]]
 name = "bech32"
@@ -2244,7 +2249,7 @@ dependencies = [
  "bitflags 2.10.0",
  "cexpr",
  "clang-sys",
- "itertools 0.12.1",
+ "itertools 0.10.5",
  "lazy_static",
  "lazycell",
  "log",
@@ -2841,9 +2846,9 @@ dependencies = [
 
 [[package]]
 name = "clap_lex"
-version = "0.7.7"
+version = "0.7.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c3e64b0cc0439b12df2fa678eae89a1c56a529fd067a9115f7827f1fffd22b32"
+checksum = "a1d728cc89cf3aee9ff92b05e62b19ee65a02b5702cff7d5a377e32c6ae29d8d"
 
 [[package]]
 name = "cmake"
@@ -2967,9 +2972,9 @@ dependencies = [
 
 [[package]]
 name = "compression-codecs"
-version = "0.4.36"
+version = "0.4.35"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "00828ba6fd27b45a448e57dbfe84f1029d4c9f26b368157e9a448a5f49a2ec2a"
+checksum = "b0f7ac3e5b97fdce45e8922fb05cae2c37f7bbd63d30dd94821dacfd8f3f2bf2"
 dependencies = [
  "brotli",
  "compression-core",
@@ -3456,15 +3461,15 @@ dependencies = [
 
 [[package]]
 name = "data-encoding"
-version = "2.10.0"
+version = "2.9.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d7a1e2f27636f116493b8b860f5546edb47c8d8f8ea73e1d2a20be88e28d1fea"
+checksum = "2a2330da5de22e8a3cb63252ce2abb30116bf5265e89c0e01bc17015ce30a476"
 
 [[package]]
 name = "data-encoding-macro"
-version = "0.1.19"
+version = "0.1.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8142a83c17aa9461d637e649271eae18bf2edd00e91f2e105df36c3c16355bdb"
+checksum = "47ce6c96ea0102f01122a185683611bd5ac8d99e62bc59dd12e6bda344ee673d"
 dependencies = [
  "data-encoding",
  "data-encoding-macro-internal",
@@ -3472,9 +3477,9 @@ dependencies = [
 
 [[package]]
 name = "data-encoding-macro-internal"
-version = "0.1.17"
+version = "0.1.16"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7ab67060fc6b8ef687992d439ca0fa36e7ed17e9a0b16b25b601e8757df720de"
+checksum = "8d162beedaa69905488a8da94f5ac3edb4dd4788b732fadb7bd120b2625c1976"
 dependencies = [
  "data-encoding",
  "syn 2.0.114",
@@ -4189,9 +4194,9 @@ dependencies = [
 
 [[package]]
 name = "flate2"
-version = "1.1.8"
+version = "1.1.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b375d6465b98090a5f25b1c7703f3859783755aa9a80433b36e0379a3ec2f369"
+checksum = "bfe33edd8e85a12a67454e37f8c75e730830d83e313556ab9ebf9ee7fbeb3bfb"
 dependencies = [
  "crc32fast",
  "miniz_oxide",
@@ -4410,9 +4415,9 @@ dependencies = [
 
 [[package]]
 name = "getrandom"
-version = "0.2.17"
+version = "0.2.16"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ff2abc00be7fca6ebc474524697ae276ad847ad0a6b3faa4bcb027e9a4614ad0"
+checksum = "335ff9f135e4384c8150d6f27c6daed433577f86b4750418338c01a1a2528592"
 dependencies = [
  "cfg-if",
  "js-sys",
@@ -5397,15 +5402,6 @@ dependencies = [
  "either",
 ]
 
-[[package]]
-name = "itertools"
-version = "0.12.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ba291022dbbd398a455acf126c1e341954079855bc60dfdda641363bd6922569"
-dependencies = [
- "either",
-]
-
 [[package]]
 name = "itertools"
 version = "0.13.0"
@@ -5808,7 +5804,7 @@ dependencies = [
  "either",
  "futures",
  "futures-timer",
- "getrandom 0.2.17",
+ "getrandom 0.2.16",
  "libp2p-allow-block-list",
  "libp2p-autonat",
  "libp2p-connection-limits",
@@ -6288,6 +6284,15 @@ dependencies = [
  "hashbrown 0.15.5",
 ]
 
+[[package]]
+name = "lru"
+version = "0.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "227748d55f2f0ab4735d87fd623798cb6b664512fe979705f829c9f81c934465"
+dependencies = [
+ "hashbrown 0.15.5",
+]
+
 [[package]]
 name = "lru"
 version = "0.16.3"
@@ -8130,9 +8135,9 @@ dependencies = [
 
 [[package]]
 name = "prost"
-version = "0.14.3"
+version = "0.14.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d2ea70524a2f82d518bce41317d0fae74151505651af45faf1ffbd6fd33f0568"
+checksum = "7231bd9b3d3d33c86b58adbac74b5ec0ad9f496b19d22801d773636feaa95f3d"
 dependencies = [
  "bytes",
  "prost-derive",
@@ -8140,9 +8145,9 @@ dependencies = [
 
 [[package]]
 name = "prost-derive"
-version = "0.14.3"
+version = "0.14.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "27c6023962132f4b30eb4c172c91ce92d933da334c59c23cddee82358ddafb0b"
+checksum = "9120690fafc389a67ba3803df527d0ec9cbbc9cc45e4cc20b332996dfb672425"
 dependencies = [
  "anyhow",
  "itertools 0.14.0",
@@ -8301,7 +8306,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6db2770f06117d490610c7488547d543617b21bfa07796d7a12f6f1bd53850d1"
 dependencies = [
  "rand_chacha 0.9.0",
- "rand_core 0.9.4",
+ "rand_core 0.9.3",
  "serde",
 ]
 
@@ -8322,7 +8327,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d3022b5f1df60f26e1ffddd6c66e8aa15de382ae63b3a0c1bfc0e4d3e3f325cb"
 dependencies = [
  "ppv-lite86",
- "rand_core 0.9.4",
+ "rand_core 0.9.3",
 ]
 
 [[package]]
@@ -8331,14 +8336,14 @@ version = "0.6.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
 dependencies = [
- "getrandom 0.2.17",
+ "getrandom 0.2.16",
 ]
 
 [[package]]
 name = "rand_core"
-version = "0.9.4"
+version = "0.9.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4f1b3bc831f92381018fd9c6350b917c7b21f1eed35a65a51900e0e55a3d7afa"
+checksum = "99d9a13982dcf210057a8a78572b2217b667c3beacbf3a0d8b454f6f82837d38"
 dependencies = [
  "getrandom 0.3.4",
  "serde",
@@ -8350,7 +8355,7 @@ version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "513962919efc330f829edb2535844d1b912b0fbe2ca165d613e4e8788bb05a5a"
 dependencies = [
- "rand_core 0.9.4",
+ "rand_core 0.9.3",
 ]
 
 [[package]]
@@ -8359,14 +8364,14 @@ version = "0.7.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f703f4665700daf5512dcca5f43afa6af89f09db47fb56be587f80636bda2d41"
 dependencies = [
- "rand_core 0.9.4",
+ "rand_core 0.9.3",
 ]
 
 [[package]]
 name = "rapidhash"
-version = "4.2.1"
+version = "4.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5d8b5b858a440a0bc02625b62dd95131b9201aa9f69f411195dd4a7cfb1de3d7"
+checksum = "2988730ee014541157f48ce4dcc603940e00915edc3c7f9a8d78092256bb2493"
 dependencies = [
  "rand 0.9.2",
  "rustversion",
@@ -8474,7 +8479,7 @@ version = "0.4.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ba009ff324d1fc1b900bd1fdb31564febe58a8ccc8a6fdbb93b543d33b13ca43"
 dependencies = [
- "getrandom 0.2.17",
+ "getrandom 0.2.16",
  "libredox",
  "thiserror 1.0.69",
 ]
@@ -8485,7 +8490,7 @@ version = "0.5.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a4e608c6638b9c18977b00b475ac1f28d14e84b27d8d42f70e0bf1e3dec127ac"
 dependencies = [
- "getrandom 0.2.17",
+ "getrandom 0.2.16",
  "libredox",
  "thiserror 2.0.17",
 ]
@@ -11980,7 +11985,7 @@ checksum = "a4689e6c2294d81e88dc6261c768b63bc4fcdb852be6d1352498b114f61383b7"
 dependencies = [
  "cc",
  "cfg-if",
- "getrandom 0.2.17",
+ "getrandom 0.2.16",
  "libc",
  "untrusted",
  "windows-sys 0.52.0",
@@ -13753,9 +13758,9 @@ dependencies = [
 
 [[package]]
 name = "tower"
-version = "0.5.3"
+version = "0.5.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ebe5ef63511595f1344e2d5cfa636d973292adc0eec1f0ad45fae9f0851ab1d4"
+checksum = "d039ad9159c98b70ecfd540b2573b97f7f52c3e8d9f8ad57a24b916a536975f9"
 dependencies = [
  "futures-core",
  "futures-util",
@@ -13905,13 +13910,16 @@ dependencies = [
 
 [[package]]
 name = "tracing-opentelemetry"
-version = "0.32.1"
+version = "0.32.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1ac28f2d093c6c477eaa76b23525478f38de514fa9aeb1285738d4b97a9552fc"
+checksum = "1e6e5658463dd88089aba75c7791e1d3120633b1bfde22478b28f625a9bb1b8e"
 dependencies = [
  "js-sys",
  "opentelemetry",
+ "opentelemetry_sdk",
+ "rustversion",
  "smallvec",
+ "thiserror 2.0.17",
  "tracing",
  "tracing-core",
  "tracing-log",
@@ -14014,7 +14022,7 @@ checksum = "78ea9ccde878b029392ac97b5be1f470173d06ea41d18ad0bb3c92794c16a0f2"
 dependencies = [
  "bitfield 0.14.0",
  "enumflags2",
- "getrandom 0.2.17",
+ "getrandom 0.2.16",
  "hostname-validator",
  "log",
  "mbox",
@@ -15440,9 +15448,9 @@ dependencies = [
 
 [[package]]
 name = "zmij"
-version = "1.0.13"
+version = "1.0.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ac93432f5b761b22864c774aac244fa5c0fd877678a4c37ebf6cf42208f9c9ec"
+checksum = "2fc5a66a20078bf1251bde995aa2fdcc4b800c70b5d92dd2c62abc5c60f679f8"
 
 [[package]]
 name = "zstd"
diff --git a/Cargo.toml b/Cargo.toml
index e727a771..14748950 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -105,6 +105,7 @@ reth-node-api = { git = "https://github.com/paradigmxyz/reth", tag = "v1.9.3" }
 reth-rpc-engine-api = { git = "https://github.com/paradigmxyz/reth", tag = "v1.9.3" }
 reth-node-ethereum = { git = "https://github.com/paradigmxyz/reth", tag = "v1.9.3" }
 reth-trie = { git = "https://github.com/paradigmxyz/reth", tag = "v1.9.3" }
+reth-trie-common = { git = "https://github.com/paradigmxyz/reth", tag = "v1.9.3" }
 reth-trie-parallel = { git = "https://github.com/paradigmxyz/reth", tag = "v1.9.3" }
 reth-basic-payload-builder = { git = "https://github.com/paradigmxyz/reth", tag = "v1.9.3" }
 reth-chainspec = { git = "https://github.com/paradigmxyz/reth", tag = "v1.9.3" }
diff --git a/crates/client/metering/Cargo.toml b/crates/client/metering/Cargo.toml
index c7147d0c..3d137822 100644
--- a/crates/client/metering/Cargo.toml
+++ b/crates/client/metering/Cargo.toml
@@ -25,6 +25,7 @@ reth-optimism-evm.workspace = true
 reth-optimism-chainspec.workspace = true
 reth-optimism-primitives.workspace = true
 reth-revm.workspace = true
+reth-trie-common.workspace = true
 
 # revm
 revm-database.workspace = true
@@ -38,6 +39,9 @@ alloy-eips.workspace = true
 jsonrpsee.workspace = true
 
 # misc
+arc-swap.workspace = true
+metrics.workspace = true
+metrics-derive.workspace = true
 tracing.workspace = true
 eyre.workspace = true
 serde.workspace = true
diff --git a/crates/client/metering/src/lib.rs b/crates/client/metering/src/lib.rs
index 5c2d89a9..299c5c3c 100644
--- a/crates/client/metering/src/lib.rs
+++ b/crates/client/metering/src/lib.rs
@@ -10,7 +10,9 @@ mod extension;
 pub use extension::{MeteringConfig, MeteringExtension};
 
 mod meter;
-pub use meter::{FlashblocksState, MeterBundleOutput, meter_bundle};
+pub use meter::{MeterBundleOutput, PendingState, PendingTrieInput, meter_bundle};
+
+mod metrics;
 
 mod rpc;
 pub use rpc::MeteringApiImpl;
@@ -18,5 +20,8 @@ pub use rpc::MeteringApiImpl;
 mod traits;
 pub use traits::MeteringApiServer;
 
+mod trie_cache;
+pub use trie_cache::PendingTrieCache;
+
 mod types;
 pub use types::{MeterBlockResponse, MeterBlockTransactions};
diff --git a/crates/client/metering/src/meter.rs b/crates/client/metering/src/meter.rs
index 5fc38636..cf21ab04 100644
--- a/crates/client/metering/src/meter.rs
+++ b/crates/client/metering/src/meter.rs
@@ -11,13 +11,58 @@ use reth_optimism_chainspec::OpChainSpec;
 use reth_optimism_evm::{OpEvmConfig, OpNextBlockEnvAttributes};
 use reth_primitives_traits::SealedHeader;
 use reth_revm::{database::StateProviderDatabase, db::State};
+use reth_trie_common::TrieInput;
 use revm_database::states::{BundleState, bundle_state::BundleRetention};
 
-/// State from pending flashblocks that is used as a base for metering
+use crate::metrics::Metrics;
+
+/// Computes the pending trie input from the bundle state.
+///
+/// This function records metrics for cache misses and compute duration.
+pub(crate) fn compute_pending_trie_input<SP>(
+    state_provider: &SP,
+    bundle_state: &BundleState,
+    metrics: &Metrics,
+) -> EyreResult<PendingTrieInput>
+where
+    SP: reth_provider::StateProvider + ?Sized,
+{
+    metrics.pending_trie_cache_misses.increment(1);
+    let start = Instant::now();
+
+    let hashed = state_provider.hashed_post_state(bundle_state);
+    let (_state_root, trie_updates) = state_provider.state_root_with_updates(hashed.clone())?;
+
+    let elapsed = start.elapsed();
+    metrics.pending_trie_compute_duration.record(elapsed.as_secs_f64());
+
+    Ok(PendingTrieInput { trie_updates, hashed_state: hashed })
+}
+
+/// Pre-computed trie input from pending state for efficient state root calculation.
+///
+/// When metering bundles on top of pending flashblocks, we first compute the trie updates
+/// and hashed state for the pending state. This can then be prepended to the bundle's
+/// trie input, so state root calculation only performs I/O for the bundle's changes.
+#[derive(Debug, Clone)]
+pub struct PendingTrieInput {
+    /// Trie updates from computing pending state root.
+    pub trie_updates: reth_trie_common::updates::TrieUpdates,
+    /// Hashed state from pending flashblocks.
+    pub hashed_state: reth_trie_common::HashedPostState,
+}
+
+/// Pending state from flashblocks used as the base for bundle metering.
+///
+/// This contains the accumulated state changes from pending flashblocks,
+/// allowing bundle simulation to build on top of not-yet-canonical state.
 #[derive(Debug, Clone)]
-pub struct FlashblocksState {
-    /// The accumulated bundle of state changes
+pub struct PendingState {
+    /// The accumulated bundle of state changes from pending flashblocks.
     pub bundle_state: BundleState,
+    /// Optional pre-computed trie input for faster state root calculation.
+    /// If provided, state root calculation skips recomputing the pending state's trie.
+    pub trie_input: Option<PendingTrieInput>,
 }
 
 const BLOCK_TIME: u64 = 2; // 2 seconds per block
@@ -39,9 +84,9 @@ pub struct MeterBundleOutput {
     pub state_root_time_us: u128,
 }
 
-/// Simulates and meters a bundle of transactions
+/// Simulates and meters a bundle of transactions.
 ///
-/// Takes a state provider, chain spec, parsed bundle, block header, and optional flashblocks state,
+/// Takes a state provider, chain spec, parsed bundle, block header, and optional pending state,
 /// then executes transactions in sequence to measure gas usage and execution time.
 ///
 /// Returns [`MeterBundleOutput`] containing transaction results and aggregated metrics.
@@ -50,7 +95,7 @@ pub fn meter_bundle<SP>(
     chain_spec: Arc<OpChainSpec>,
     bundle: ParsedBundle,
     header: &SealedHeader,
-    flashblocks_state: Option<FlashblocksState>,
+    pending_state: Option<PendingState>,
 ) -> EyreResult<MeterBundleOutput>
 where
     SP: reth_provider::StateProvider,
@@ -58,17 +103,34 @@ where
     // Get bundle hash
     let bundle_hash = bundle.bundle_hash();
 
+    // Get pending trie input before starting timers. This ensures we only measure
+    // the bundle's incremental I/O cost, not I/O from pending flashblocks.
+    let metrics = Metrics::default();
+    let pending_trie = pending_state
+        .as_ref()
+        .map(|ps| -> EyreResult<PendingTrieInput> {
+            // Use cached trie input if available, otherwise compute it
+            if let Some(ref cached) = ps.trie_input {
+                metrics.pending_trie_cache_hits.increment(1);
+                Ok(cached.clone())
+            } else {
+                compute_pending_trie_input(&state_provider, &ps.bundle_state, &metrics)
+            }
+        })
+        .transpose()?;
+
     // Create state database
     let state_db = StateProviderDatabase::new(state_provider);
 
-    // Track bundle state changes. If metering using flashblocks state, include its bundle prestate.
-    let mut db = match flashblocks_state {
-        Some(ref flashblocks) => State::builder()
+    // Track bundle state changes. If metering with pending state, include it as bundle prestate.
+    let mut db = if let Some(ref ps) = pending_state {
+        State::builder()
             .with_database(state_db)
             .with_bundle_update()
-            .with_bundle_prestate(flashblocks.bundle_state.clone())
-            .build(),
-        None => State::builder().with_database(state_db).with_bundle_update().build(),
+            .with_bundle_prestate(ps.bundle_state.clone())
+            .build()
+    } else {
+        State::builder().with_database(state_db).with_bundle_update().build()
     };
 
     // Set up next block attributes
@@ -129,14 +191,25 @@ where
     }
 
     // Calculate state root and measure its calculation time. The bundle already includes
-    // flashblocks state if it was provided via with_bundle_prestate.
+    // pending state if it was provided via with_bundle_prestate.
     db.merge_transitions(BundleRetention::Reverts);
     let bundle_update = db.take_bundle();
     let state_provider = db.database.as_ref();
 
     let state_root_start = Instant::now();
     let hashed_state = state_provider.hashed_post_state(&bundle_update);
-    let _ = state_provider.state_root_with_updates(hashed_state)?;
+
+    if let Some(cached_trie) = pending_trie {
+        // Prepend cached pending trie so state root calculation only performs I/O
+        // for this bundle's changes, not for pending flashblocks.
+        let mut trie_input = TrieInput::from_state(hashed_state);
+        trie_input.prepend_cached(cached_trie.trie_updates, cached_trie.hashed_state);
+        let _ = state_provider.state_root_from_nodes_with_updates(trie_input)?;
+    } else {
+        // No pending state, just calculate bundle state root
+        let _ = state_provider.state_root_with_updates(hashed_state)?;
+    }
+
     let state_root_time_us = state_root_start.elapsed().as_micros();
     let total_time_us = total_start.elapsed().as_micros();
 
@@ -446,7 +519,7 @@ mod tests {
             harness.chain_spec(),
             parsed_bundle.clone(),
             &header,
-            None, // No flashblocks state
+            None, // No pending state
         );
 
         assert!(
@@ -454,7 +527,7 @@ mod tests {
             "Transaction with nonce=1 should fail without pending state (canonical nonce is 0)"
         );
 
-        // Now create flashblocks state with nonce=1 for Alice
+        // Now create pending state with nonce=1 for Alice
         // Use BundleState::new() to properly calculate state_size
         let bundle_state = BundleState::new(
             [(
@@ -477,26 +550,26 @@ mod tests {
             Vec::<(B256, Bytecode)>::new(),
         );
 
-        let flashblocks_state = FlashblocksState { bundle_state };
+        let pending_state = PendingState { bundle_state, trie_input: None };
 
-        // With correct flashblocks state, transaction should succeed
+        // With correct pending state, transaction should succeed
         let state_provider2 = harness
             .blockchain_provider()
             .state_by_block_hash(latest.hash())
             .context("getting state provider")?;
 
-        let result_with_flashblocks = meter_bundle(
+        let result_with_pending = meter_bundle(
             state_provider2,
             harness.chain_spec(),
             parsed_bundle,
             &header,
-            Some(flashblocks_state),
+            Some(pending_state),
         );
 
         assert!(
-            result_with_flashblocks.is_ok(),
+            result_with_pending.is_ok(),
             "Transaction with nonce=1 should succeed with pending state showing nonce=1: {:?}",
-            result_with_flashblocks.err()
+            result_with_pending.err()
         );
 
         Ok(())
diff --git a/crates/client/metering/src/metrics.rs b/crates/client/metering/src/metrics.rs
new file mode 100644
index 00000000..130e8b9d
--- /dev/null
+++ b/crates/client/metering/src/metrics.rs
@@ -0,0 +1,24 @@
+//! Metrics for bundle metering.
+
+use metrics::{Counter, Histogram};
+use metrics_derive::Metrics;
+
+/// Metrics for the `reth_metering` component.
+/// Conventions:
+/// - Durations are recorded in seconds (histograms).
+/// - Counters are monotonic event counts.
+#[derive(Metrics, Clone)]
+#[metrics(scope = "reth_metering")]
+pub(crate) struct Metrics {
+    /// Count of pending trie cache hits.
+    #[metric(describe = "Count of pending trie cache hits")]
+    pub pending_trie_cache_hits: Counter,
+
+    /// Count of pending trie cache misses (trie computation required).
+    #[metric(describe = "Count of pending trie cache misses")]
+    pub pending_trie_cache_misses: Counter,
+
+    /// Time taken to compute pending trie (cache miss).
+    #[metric(describe = "Time taken to compute pending trie on cache miss")]
+    pub pending_trie_compute_duration: Histogram,
+}
diff --git a/crates/client/metering/src/rpc.rs b/crates/client/metering/src/rpc.rs
index d08fe5da..1c706693 100644
--- a/crates/client/metering/src/rpc.rs
+++ b/crates/client/metering/src/rpc.rs
@@ -17,7 +17,7 @@ use reth_provider::{
 use tracing::{error, info};
 
 use crate::{
-    FlashblocksState, MeterBlockResponse, block::meter_block, meter::meter_bundle,
+    MeterBlockResponse, PendingState, PendingTrieCache, block::meter_block, meter::meter_bundle,
     traits::MeteringApiServer,
 };
 
@@ -25,7 +25,10 @@ use crate::{
 #[derive(Debug)]
 pub struct MeteringApiImpl<Provider, FB> {
     provider: Provider,
-    flashblocks_state: Arc<FB>,
+    flashblocks_api: Arc<FB>,
+    /// Cache for pending trie input, ensuring each bundle's state root
+    /// calculation only measures the bundle's incremental I/O.
+    pending_trie_cache: PendingTrieCache,
 }
 
 impl<Provider, FB> MeteringApiImpl<Provider, FB>
@@ -38,9 +41,9 @@ where
         + Clone,
     FB: FlashblocksAPI,
 {
-    /// Creates a new instance of MeteringApi
-    pub const fn new(provider: Provider, flashblocks_state: Arc<FB>) -> Self {
-        Self { provider, flashblocks_state }
+    /// Creates a new instance of MeteringApi.
+    pub fn new(provider: Provider, flashblocks_api: Arc<FB>) -> Self {
+        Self { provider, flashblocks_api, pending_trie_cache: PendingTrieCache::new() }
     }
 }
 
@@ -65,8 +68,8 @@ where
             "Starting bundle metering"
         );
 
-        // Get pending flashblocks state
-        let pending_blocks = self.flashblocks_state.get_pending_blocks();
+        // Get pending blocks from flashblocks API
+        let pending_blocks = self.flashblocks_api.get_pending_blocks();
 
         // Get header and flashblock index from pending blocks
         // If no pending blocks exist, fall back to latest canonical block
@@ -135,10 +138,34 @@ where
                 )
             })?;
 
-        // If we have pending flashblocks, get the state to apply pending changes
-        let flashblocks_state = pending_blocks
-            .as_ref()
-            .map(|pb| FlashblocksState { bundle_state: pb.get_bundle_state() });
+        // Get the flashblock index if we have pending blocks
+        let state_flashblock_index = pending_blocks.as_ref().map(|pb| pb.latest_flashblock_index());
+
+        // If we have pending blocks, extract the pending state for metering
+        let pending_state = if let Some(pb) = pending_blocks.as_ref() {
+            let bundle_state = pb.get_bundle_state();
+
+            // Build a temporary PendingState without trie_input to get the cached trie
+            let temp_state = PendingState { bundle_state: bundle_state.clone(), trie_input: None };
+
+            // Ensure the pending trie input is cached for reuse across bundle simulations
+            let fb_index = state_flashblock_index.unwrap();
+            let trie_input = self
+                .pending_trie_cache
+                .ensure_cached(header.hash(), fb_index, &temp_state, &*state_provider)
+                .map_err(|e| {
+                    error!(error = %e, "Failed to cache pending trie input");
+                    jsonrpsee::types::ErrorObjectOwned::owned(
+                        jsonrpsee::types::ErrorCode::InternalError.code(),
+                        format!("Failed to cache pending trie input: {}", e),
+                        None::<()>,
+                    )
+                })?;
+
+            Some(PendingState { bundle_state, trie_input: Some(trie_input) })
+        } else {
+            None
+        };
 
         // Meter bundle using utility function
         let output = meter_bundle(
@@ -146,7 +173,7 @@ where
             self.provider.chain_spec(),
             parsed_bundle,
             &header,
-            flashblocks_state,
+            pending_state,
         )
         .map_err(|e| {
             error!(error = %e, "Bundle metering failed");
@@ -182,7 +209,7 @@ where
             gas_fees: output.total_gas_fees,
             results: output.results,
             state_block_number: header.number,
-            state_flashblock_index: Some(flashblock_index),
+            state_flashblock_index,
             total_gas_used: output.total_gas_used,
             total_execution_time_us: output.total_time_us,
             state_root_time_us: output.state_root_time_us,
diff --git a/crates/client/metering/src/trie_cache.rs b/crates/client/metering/src/trie_cache.rs
new file mode 100644
index 00000000..2475345b
--- /dev/null
+++ b/crates/client/metering/src/trie_cache.rs
@@ -0,0 +1,88 @@
+//! Pending trie caching for efficient bundle metering.
+//!
+//! When metering bundles on top of pending flashblocks, we cache the pre-computed
+//! trie input so that subsequent bundle simulations can reuse it rather than
+//! recomputing the pending state root each time.
+
+use std::sync::Arc;
+
+use alloy_primitives::B256;
+use arc_swap::ArcSwap;
+use eyre::Result as EyreResult;
+use reth_provider::StateProvider;
+
+use crate::{PendingState, PendingTrieInput, meter::compute_pending_trie_input, metrics::Metrics};
+
+/// Internal cache entry for a single flashblock's pending trie input.
+#[derive(Debug, Clone)]
+struct CachedEntry {
+    block_hash: B256,
+    flashblock_index: u64,
+    trie_input: PendingTrieInput,
+}
+
+/// Thread-safe single-entry cache for pending trie input.
+///
+/// This cache stores the pre-computed trie input (trie updates and hashed state)
+/// from the latest pending flashblock. Subsequent bundle metering operations
+/// on the same flashblock can reuse this cached input instead of recomputing it,
+/// significantly improving performance.
+///
+/// **Important**: This cache holds only ONE entry at a time.
+/// When a new flashblock is cached, it replaces any previously cached entry.
+#[derive(Debug, Clone)]
+pub struct PendingTrieCache {
+    cache: Arc<ArcSwap<Option<CachedEntry>>>,
+    metrics: Metrics,
+}
+
+impl PendingTrieCache {
+    /// Creates a new empty pending trie cache.
+    pub fn new() -> Self {
+        Self { cache: Arc::new(ArcSwap::from_pointee(None)), metrics: Metrics::default() }
+    }
+
+    /// Ensures the trie input for the given flashblock is cached and returns it.
+    ///
+    /// If the cache already contains an entry for the provided `block_hash` and
+    /// `flashblock_index`, the cached data is returned immediately. Otherwise the trie
+    /// input is computed, cached (replacing any previous entry), and returned.
+    pub fn ensure_cached(
+        &self,
+        block_hash: B256,
+        flashblock_index: u64,
+        pending_state: &PendingState,
+        canonical_state_provider: &dyn StateProvider,
+    ) -> EyreResult<PendingTrieInput> {
+        let cached_entry = self.cache.load();
+        if let Some(cached) = cached_entry.as_ref()
+            && cached.block_hash == block_hash
+            && cached.flashblock_index == flashblock_index
+        {
+            self.metrics.pending_trie_cache_hits.increment(1);
+            return Ok(cached.trie_input.clone());
+        }
+
+        // Cache miss - compute the trie input with metrics
+        let trie_input = compute_pending_trie_input(
+            canonical_state_provider,
+            &pending_state.bundle_state,
+            &self.metrics,
+        )?;
+
+        // Store the new entry, replacing any previous cached entry
+        self.cache.store(Arc::new(Some(CachedEntry {
+            block_hash,
+            flashblock_index,
+            trie_input: trie_input.clone(),
+        })));
+
+        Ok(trie_input)
+    }
+}
+
+impl Default for PendingTrieCache {
+    fn default() -> Self {
+        Self::new()
+    }
+}