I just want summarize my findings, what is happening with performance during my gameplay.
My PC is i7 2600k, overclocked to 4.4ghz, GTX 1660Ti(overclocked) and 32Gb RAM and I am limiting FPS to 60 without using V-sync.
Game can hold 50-60FPS quite well on Very Hight and shadows set to medium. However some anomalies are happening .
I am playing Primalist, trying thorns build and everytime I cast thorns burst, FPS drops by several frames… like to 54-55, while staying here for several seconds and it will jumps back to my limit 60 fps. Weird is, this FPS drop is for very specific time, even when all effects from spell are no more visible.
Also during some heavy fights, with a lot of effects, FPS can drop to 20+ fps and again, stay there for several seconds. 10-20 seconds, even when nothing is happening and everything is dead on screen and I am just standing on one place. After this duration, FPS jumps back to 60 fps, without me doing anything. This is happening at the beginning of the game, in caves, where big wooden circle platforms are (not remember map name) - and only there in my short gameplay.
Another weird anomaly is, that sometimes, when I enter certain zones, FPS drop to 30 or lower for no reason. However changing Vegetation system to very low will suddenly returns FPS back to 60. Switching to even Low on Vegetation system fps is back on 30 - every settings except very low will cause this. Again, this is happening in cave locations. After walking around for minute or so, without changing anything, game can recover(sometimes) and once again be running on 60FPS even in places, where to dropped to 30 before.
I checked my temperatures and frequencies, to make sure, my PC is not throttling in any way and it is not.