For whatever reason, the game gets unbelievably laggy only when the camera is being turned. This only became as issue after the recent patches, before I was consistently getting 90 fps without any major lag spikes. I am running Linux Mint 22 as well if that matters.
Kinda of? After a while it just stopped happening for no particular reason after booting my computer up, but there were a few things I did beforehand that may have solved it. Right click properties and paste "-nojoy -no_environment_maps -high -novid -softparticlesdefaultoff +mat_disable_fancy_blending 1 +mat_queue_mode 2 +cl_forcepreload 1" into the launch options. Go into the Software Manager and download "Lutris", then right click Deadlock and configure, then go to system options and enable "Feral GameMode". I've also heard of people having lag caused by mouse polling rate. Download "Piper" from the Software Manager and lower the report rate.