Maybe it's the particle effects? When players run through snow they kick up snow particles. It's the same reason competitive players use a modded version of Coldfront that takes place in summer.
I detected the problem.
The problem is fully linked to the model of the GPU and the current resolution of my monitor (1080p).
If I reduce the resolution to the resolution of my old monitor, the game runs smoothly.
Nothing extracted yet.
In certain maps like Viaduct my FPS drops suffers constant, which does not happen when I play using Windows.
Not sure what the cause of the lag, but it only happens on ice maps.
I'm using the proprietary drivers from AMD.
Computer specification:
AMD Phenom II x4 965 3.4GHz
Ram Corsair 8GB (2x 4GB)
ATI Radeon 6670 Core Edition - 2GB
Sorry for my english.
English is not my native language.