Yeah, I have issues with random really poor frame times. I'll be sitting at 144 FPS then get some frames that take 45ms to render each/severe stuttering.
I "fixed" it using the proton version of the game though I've heard some people say that doesn't work with match making... Haven't tried that yet.
I was thinking about trying the -vulkan launch option to see if that does anything if my proton install doesn't work.
EDIT: They were right ... VAC doesn't work via Proton. I retried playing the native version and it seemed to run fine this time with or without -vulkan ... so I'm not really sure what's going on anymore.
Maybe some things have been fixed either on the Linux/Mesa or on the Valve side.