I can approve that the "set affinity" tweak (disabling cores 0 and 1 in the task manager) works for my Xeon CPU. Now the game seems to really use at least 4 cores/threads.
I think Larian should implement that tweak or solve the problem that leads to the necessarity of this tewak ASAP.
I think I read we have an incoming patch today to help performance, if it helps you, we'll see. The picture I like to paint because I think it's the most accurate is many systems run this game well, however there are some cpu's possibly gpu's and the combo's of each that something in this game doesn't like. For those people obviously the game has major issues. There has been a performance patch a day, it's helped some people out each day. Here's to today being yours!
Thanks for the ram usage numbers I haven't checked. That is what Larian warned about doing the TextureStream Tweak, it can really start to use memory. But for many users now 64 bit with a gob of memory is more like "bring it on!". But those without, will probably now see more memory crashed. Without the TextureStream tweak I believe the game is only taking up about a gig of ram. So one needs to weigh both sides.