Installing fresh driver fixed it, but I got some strange lags instead
Game can now freeze for 5 seconds showing some strange color artifacts and eventually gets back to a normal state. I get it only playing online, offline game works perfectly smooth.
I'll test it tomorrow to see if it's happening on all servers...
About the framerate: I use force V-sync so in most cases fps is far above 60. It drops down to 50 only when theres a lot of cars in sight. I can't tell what's the top fps as counter clamps everything above 60.
It's hard to tell when it's started. 2 months maybe. It was working just fine with all directx mods I'm using, with Vista x64 sp1.
It could be some windows hotfix or a driver update, hard to tell.
Anyway, I'm planing to install w7 this week. I'll make a fresh lfs installation without all mods to see how it behaves.