nVidia performence and quality

[Alexander Jones]

ALL of this stuff should be on Answers.launchpad.net, but I will
answer anyway as I am bored.

Compiz limits its redraws usually, the benchmark plugin has an option
to temporarily disable the "frame limiter" whilst benchmarking. Check
that this feature hasn't been disabled in Compiz's settings.

As for the remaining two issues, check VSync, check benchmarks, check
without Composite.