We ran Bork for some Java-powered encryption and its performance improved slightly in each kernel release until Linux 2.6.32 where it ran the best, but with Linux 2.6.33 it has negatively regressed.
Our PostMark disk benchmark results were similar to that of PostgreSQL where with the Linux 2.6.30 kernel its transactional performance improved greatly, but with the latest Linux kernel, these gains have been completely erased.
Dbench with one client falls into a similar boat with PostgreSQL and PostMark in terms of gains during the Linux 2.6.30 kernel development that were sustained with the 2.6.31 and 2.6.32 releases but then completely wiped away with the 2.6.33 release.
When running multiple Dbench clients it was a different story than when having only one client accountable. With 12 clients, there was a sizable gain between the 2.6.29 and 2.6.30 kernels that lived on with Linux 2.6.31 and 2.6.32, but this time with 2.6.33 its performance jumped even higher. However, judging by the jump, there may be some system memory caching involved.