The input lag is ridiculous with vsync on. I'm not even talking about in the game, I'm talking about the main menu. It's not a frame rate issue, it happens with low or high video settings selected. This is worse than on any game I've seen. I am picky about input lag, but even if I wasn't, I would notice this. Anyone would notice this.

I tried the Smoothness = 0 fixes and they helped somewhat, but it's still a big problem. I also tried disabling all acceleration and other nonsense from my mouse drivers.

I tried forcing triple buffering with D3DOverride but it didn't help.

Is there any way I can adjust how many frames are being buffered for vsync, or anything?

Disabling vsync instantly fixes the problem (regardless of all other video settings).

I don't think it matters, but I use a Radeon 6950.

So strange...mouse is perfectly responsive here, with or without v-sync, and without any tweaking...

After messing about with the mouse settings (in Windows, in the mouse driver, in the game settings and in the game's .ini file - isn't it great there are four places to change things?) I've mitigated the issue to the point where it is merely annoying.