Just an update to this thread. It seems to be PC specific. I found that after testing with additional hardware it appears to be limited to just my PC (2080 and i7-5820k). Might be worthwhile to test on other PCs if you run into this. Even on lower hardware (a 1080 with no DLSS) it did not have this issue.
My “best” guess is it has something to do with Auto DLSS settings as I can get closer if I set it UltraPerformance on both builds. Strangely turning DLSS off tanks my performance in both builds from 70FPS to 1 FPS, so something is going on there.
Reinstalling a clean video card driver, doing sfc /scannow, and clean installing the game multiple times had no effect.
I’ll update again if I figure out how to get back to normal performance.