Running Ubuntu 16.04 with POL and World of Tanks, recently update 9.17 for WOT and was noticed in CT server before update caused the graphics to be so sluggish that the mouse pointer had lag and the intro video looked like stop motion. Graphics Nvidia 8 GB GTX 1070 with 2048 CUDA Cores is the harware with proprietry drivers for my machine.
Solution: So simple but took week to figure. From full screen when the graphics are sluggish take the screen boarder and pull it less then full screen, you might have to goto settings in WOT and change the windows from Fullscreen to Boardered if you can. Its painful but might have to be done. You will notice a 100% improvment after the screen is out of fullscreen mode.
Update: select windowed boarderless in WOT graphic settings. Problem cured 127 FPS!!