diff --git a/async_substrate_interface/async_substrate.py b/async_substrate_interface/async_substrate.py
index 90ac49d..9901619 100644
--- a/async_substrate_interface/async_substrate.py
+++ b/async_substrate_interface/async_substrate.py
@@ -11,6 +11,7 @@
 import socket
 import ssl
 import warnings
+from contextlib import suppress
 from unittest.mock import AsyncMock
 from hashlib import blake2b
 from typing import (
@@ -1211,6 +1212,8 @@ def __init__(
         self.metadata_version_hex = "0x0f000000"  # v15
         self._initializing = False
         self._mock = _mock
+        self.startup_runtime_task: Optional[asyncio.Task] = None
+        self.startup_block_hash: Optional[str] = None
 
     async def __aenter__(self):
         if not self._mock:
@@ -1230,8 +1233,12 @@ async def _initialize(self) -> None:
             if not self._chain:
                 chain = await self.rpc_request("system_chain", [])
                 self._chain = chain.get("result")
-            runtime = await self.init_runtime()
+            self.startup_block_hash = block_hash = await self.get_chain_head()
+            self.startup_runtime_task = asyncio.create_task(
+                self.init_runtime(block_hash=block_hash, init=True)
+            )
             if self.ss58_format is None:
+                runtime = await self.init_runtime(block_hash)
                 # Check and apply runtime constants
                 ss58_prefix_constant = await self.get_constant(
                     "System", "SS58Prefix", runtime=runtime
@@ -1438,7 +1445,10 @@ async def decode_scale(
             return obj
 
     async def init_runtime(
-        self, block_hash: Optional[str] = None, block_id: Optional[int] = None
+        self,
+        block_hash: Optional[str] = None,
+        block_id: Optional[int] = None,
+        init: bool = False,
     ) -> Runtime:
         """
         This method is used by all other methods that deals with metadata and types defined in the type registry.
@@ -1455,6 +1465,13 @@ async def init_runtime(
         Returns:
             Runtime object
         """
+        if (
+            not init
+            and self.startup_runtime_task is not None
+            and block_hash == self.startup_block_hash
+        ):
+            await self.startup_runtime_task
+            self.startup_runtime_task = None
 
         if block_id and block_hash:
             raise ValueError("Cannot provide block_hash and block_id at the same time")
@@ -4322,6 +4339,10 @@ async def close(self):
         Closes the substrate connection, and the websocket connection.
         """
         try:
+            if self.startup_runtime_task is not None:
+                self.startup_runtime_task.cancel()
+                with suppress(asyncio.CancelledError):
+                    await self.startup_runtime_task
             await self.ws.shutdown()
         except AttributeError:
             pass
diff --git a/tests/integration_tests/test_disk_cache.py b/tests/integration_tests/test_disk_cache.py
index 063eca1..11e7312 100644
--- a/tests/integration_tests/test_disk_cache.py
+++ b/tests/integration_tests/test_disk_cache.py
@@ -88,44 +88,44 @@ async def test_disk_cache():
         start = time.monotonic()
         new_block_hash = await disk_cached_substrate.get_block_hash(current_block)
         new_time = time.monotonic()
-        assert new_time - start < 0.001
+        assert new_time - start < 0.002
 
         start = time.monotonic()
         new_parent_block_hash = await disk_cached_substrate.get_parent_block_hash(
             block_hash
         )
         new_time = time.monotonic()
-        assert new_time - start < 0.001
+        assert new_time - start < 0.002
         start = time.monotonic()
         new_block_runtime_info = await disk_cached_substrate.get_block_runtime_info(
             block_hash
         )
         new_time = time.monotonic()
-        assert new_time - start < 0.001
+        assert new_time - start < 0.002
         start = time.monotonic()
         new_block_runtime_version_for = (
             await disk_cached_substrate.get_block_runtime_version_for(block_hash)
         )
         new_time = time.monotonic()
-        assert new_time - start < 0.001
+        assert new_time - start < 0.002
         start = time.monotonic()
         new_block_hash_from_cache = await disk_cached_substrate.get_block_hash(
             current_block
         )
         new_time = time.monotonic()
-        assert new_time - start < 0.001
+        assert new_time - start < 0.002
         start = time.monotonic()
         new_parent_block_hash_from_cache = (
             await disk_cached_substrate.get_parent_block_hash(block_hash_from_cache)
         )
         new_time = time.monotonic()
-        assert new_time - start < 0.001
+        assert new_time - start < 0.002
         start = time.monotonic()
         new_block_runtime_info_from_cache = (
             await disk_cached_substrate.get_block_runtime_info(block_hash_from_cache)
         )
         new_time = time.monotonic()
-        assert new_time - start < 0.001
+        assert new_time - start < 0.002
         start = time.monotonic()
         new_block_runtime_version_from_cache = (
             await disk_cached_substrate.get_block_runtime_version_for(
@@ -133,5 +133,5 @@ async def test_disk_cache():
             )
         )
         new_time = time.monotonic()
-        assert new_time - start < 0.001
+        assert new_time - start < 0.002
     print("Disk Cache tests passed")
diff --git a/tests/unit_tests/asyncio_/test_substrate_interface.py b/tests/unit_tests/asyncio_/test_substrate_interface.py
index afefe7a..a0ac123 100644
--- a/tests/unit_tests/asyncio_/test_substrate_interface.py
+++ b/tests/unit_tests/asyncio_/test_substrate_interface.py
@@ -296,7 +296,9 @@ async def test_get_account_next_index_cached_mode_uses_internal_cache():
     substrate.supports_rpc_method = AsyncMock(return_value=True)
     substrate.rpc_request = AsyncMock(return_value={"result": 5})
 
-    first = await substrate.get_account_next_index("5F3sa2TJAWMqDhXG6jhV4N8ko9NoFz5Y2s8vS8uM9f7v7mA")
+    first = await substrate.get_account_next_index(
+        "5F3sa2TJAWMqDhXG6jhV4N8ko9NoFz5Y2s8vS8uM9f7v7mA"
+    )
     second = await substrate.get_account_next_index(
         "5F3sa2TJAWMqDhXG6jhV4N8ko9NoFz5Y2s8vS8uM9f7v7mA"
     )
@@ -331,7 +333,9 @@ async def test_get_account_next_index_bypass_mode_does_not_create_or_mutate_cach
 async def test_get_account_next_index_bypass_mode_raises_on_rpc_error():
     substrate = AsyncSubstrateInterface("ws://localhost", _mock=True)
     substrate.supports_rpc_method = AsyncMock(return_value=True)
-    substrate.rpc_request = AsyncMock(return_value={"error": {"message": "rpc failure"}})
+    substrate.rpc_request = AsyncMock(
+        return_value={"error": {"message": "rpc failure"}}
+    )
 
     with pytest.raises(SubstrateRequestException, match="rpc failure"):
         await substrate.get_account_next_index(