All of those steps that u mentioned above I've done when chupacabra answered me on the first ticket that i made;
About this,i play in 1920 x 1080p resolution in POTATO settings, V-Sync OFF, antialising off and ssao OFF, Fast load OFF and the option of disable item Pyshx don't seems that has any affect on my fps because with turned on or off it stays the same low fps, cities with too many people makes the fps drop a lot and freezes much too.
I saw a streamer with the same settings playing infestation,he has a ryzen 5 1600x that only has the clock base and boost faster than mine but mine is overclocked at 3.6 on all cores and he has 16gb of ram, I only have 8 but it seems that this don't have so many impact. He was playing with Fast load ON and he's fps was like 40/50/60 all the time in caliwood with some textures and terrain in high(with fast load ON i've noticed that has an up of 20 fps) It means that with the Fast load OFF he should have 20/30 fps at all times,
As jewdiciousorange "The game seems poorly optimized for AMD hardware in general" I'm not a developer or something like that,but this sentence makes so much sense to me as i ask to my friends with intel computers and has higher fps, above 100+.