Just to add another data point, I have the same experience on windows and haven’t been able to solve it. I’m on windows 10, also an 8700k, and an RTX 3090. This build has no issues running modern stuff like cyberpunk /w ultra raytracing, starfield, bg3, etc.
Performance was never perfect but it absolutely tanked a few major updates ago. I THINK it was around the time the performance issues cropped up on the series x as well.
If you find any cause other than just “doesn’t play nice with older Intel CPUs” I’d love to know.
The run energy changes - I think it’s worth rebalancing but I just hope they don’t change it so much that you can sprint through the early game. I feel like a big part of getting attached to the world is plodding your way through it at the beginning.