Game run stable at 25/30 fps but could reach 60 with a previous version of proton. Fire effects and explosion are incisive to the fps. Proton 4.11-13 is the only one I can have enabled to reach 60 fps, but the missing flames from flamethrower and enemies molotov are invisible, and the game is unplayable like this. To resume, Proton 4.11-13 to have max fps but invisible flames, everything else to play normally but with costant fps drop and stuttering.