Hi Bluutar, well i done something that's for sure bacause when i first was playing it i was at around 50fps with these horrible slowdowns too, now i'm all good with around 90 -100% gpu usage and no distracting slowdowns, with the slowdowns i was also getting low gpu usage.
Sure i'll post everything i done and post pics of my CVar config settings too, but i'll do that last.
First, make sure your system is ocED TO THE MAX (gpu + cpu + ram) but it must be stable of course.
Next, try different drivers (with the laters GeForce drivers i had multi driver crashes but not so with the quadro drivers -i've started using thse quadros with a moded .inf file).
set frame rate limit to 60, in-game v sync disabled and nvidia adaptive v sync enabled (if you have nvidia card).
use the command in the console r_PostMSAA = 0
To use the CVar configurator first set in-game settings THEN the configurator.