I've posted it already to ql board but I guess they don't have linux developer atm so I'm posting it here too. Next in a row is icculus and freedesktop bugzillas (although every bug report I posted to freedesktop bugzilla so far took at least half a year to get response).

There is mouse input lag under linux compared to windows xp on my system (or display delay)b.


Here are the results of tests I've made so far.

1. Windows - no perceived input lag in any game
2. Linux QL - mouse input lag
3. Linux quake3 icculus - exactly the same input lag as in ql
4. Linux quake2 icculus - much better than linux-q3, I haven't compared it directly to windows-ql yet but I think it's the same or very similiar (I thought that q2 engine had internal 20ms mouse input lag?)

Here are my system's specs:
Intel GMA M4500HD graphics card (mobile)
WMO mouse running at 250 Hz (in both OS)
120 Hz CRT monitor connected by analog VGA cable

linux kernel 3.4.3
xorg-server 1.12.2
xf86-video-intel 2.19.0
mesa 8.0.3

I've been experiencing it for at least a year with various software configurations.
It may be as trivial as some kernel config option or some xinput setting. But it may need a fix in ql/q3 code or even upstream. If you have idea why does it happen in q3 but not in q2 or any propositions pls let me know.

Here is the thread on ql forums.