Other optimisations to consider that will tweak it more:
* Build your own custom kernel, compile the OS and packages with optimised settings. In the past this could give up to 10% or more improvements on generic linux distro installs. These days I doubt it would be close to that, but it still should be a couple of percent.
* Overclock, CPU of course, but tweaking the memory timings/settings I've heard can give great results.
* RAID set up on disks.
...but that requires a bit of work, so it's probably easier to enjoy what you've got.
