...*cough*
So anyway, the steam page listing the changes to the experimental branch:
https://steamcommunity.com/app/275850/discussions/7/360672304897578119/
..To Gog-people - wouldn't mind if it became available to us as well.
Things of moderate interest:
"Max FPS Cap
On some CPU/GPU configurations, setting Max FPS to 60 or 30 was not giving 60 or 30 FPS (causing stuttering). This has been improved."
Wouldn't mind if they just avoided explicit screen-context references altogether, but that's nice.
"Improved AMD Phenom Support
Thousands of lines of assembly have been rewritten overnight to support AMD CPUs. Unfortunately whilst the game code no longer relies on anything above SSE 2, Havok Physics still requires “Supplemental SSE 3”, which was not supported until “Bobcat” and above. We’re discussing with Havok."
I guess the word you were looking for was "recompiled" :p, even if I'm sure they've rewritten a lot as well ("let's remove all dependency on sse3 overnight" - worst coder assignment ever). And that was fun, because it likely means my holistic debug scrying was randomly correct somehow: that indirectly, what's causing the amazing slowdowns for a lot of people is thread starvation with Havok routines (...that probably are extremely lightweight in the scheme of things, but need their own explicit context).
If Gog is collecting things for feedback, by the way, here's my personal things on just the technical stuff:
-Run-time of per pixel type physics operations (likely) in Havok depending on screen resolution. I can... live without fluttering space-cale if it means avoiding drops to 5fps, or if I can increase the resolution three times without any framedrops (i.e., I prefer no full-screen post-treatment, and frankly the aesthetic in the game requires it too).
-Extra surface shader effects and volumentric smoke type effects with per frame adjustment results - really, just get rid of it instead of tweaking. It's ugly, and it's bound to cause issues for everyone on any rig when you have fifty billion surfaces to refract lighting off. And even if it does technically complete perfectly, the shadows cast will be inaccurate and are bound to highlight the unmatching "sectors" of the geometry nearby, instead of giving the nearest perfectly flat surface a "glow" like in other games.
-And are you running some sort of colour-correction full-screen blur filter? Please consider not doing that, in spite of Sony.