Mouse Lag on High Frame Rates

hi,

i experienced a strange behavior.

after setting the frame cap to 125 fps or even higher i have an extreme input lag. it feels like using a "lightning gun" with net lag :) this lang increasing proportionally with the framerate. when i cap the framerate to 60 fps the lag gets lower.

any hints on how to fix this?

greetz,

mingy

edit:

i recognized setting gl_finish to 1 removes the lag but lowers framereates immense

hardware spec:

pentium-m 1.8 ghz
ddr2 1024 mb ram
ati x700

software:
linux gentoo 2006.0
ati driver 8.25.18 xorg 6.8.2