Take 10_000_000 rows, open it in a table widget in notebooks and sort by a column
Sorting and loading take a lot of time. I don't have a profile so i can't say for sure where's the actual bottleneck, it needs to be investigated
However this method performs sorting of the entire dataframe, all 10 million rows even when only 20 or 100 are going to be displayed. There's more efficient algorithms for such situations, for example least or greatest from Guava: https://guava.dev/releases/snapshot-jre/api/docs/com/google/common/collect/Comparators.html#least(int,java.util.Comparator)