I was messing with every setting possible then I noticed on non-PB servers my mouse and FPS were super stable and accurate (even with vsync on).

So I got to thinking and recall back in the Quake 3 early PB days often a few tweaks with the PB config made a huge difference.

I put the following in the /pb/pbsys.cfg:

pb_system 0

It was default 1 before. Now my mouse is very accurate and FPS is very stable.

pb_system 0/1 doesn't turn PB on and off, it only changes the way PB uses memory and such.

Also try tweaking pb_sleep .. for some reason for me pb_sleep 20 is the best, no idea why.

Hope this helps someone out there.