Decided to jump back in and see if the new patches did anything. My system specs:
GTX 970
i5 3570k (not OC'ed, yeah yeah I know)
16GB DDR3-1600
I run at 1920x1200. Even after dropping everything to low and closing most of my open applications (something I haven't had to do to make a game run okay in years), I still see my system struggling to hit solid 30fps. Removed vsync and the frame limiter in-game and used Nvidia Inspector to enforce vsync and set a 45fps cap, still nothing. Even at this almost-30fps, the game action speeds up and slows down constantly, making it hard to do any sort of precision driving. It's a hot mess.
Until I use Windows 10's built-in recording tools to start a recording. As soon as I do that, THEN the framerate suddenly jumps to 45fps and the lurching back and forth seems to mostly disappear, which is the total opposite of what you'd expect (recording being more intensive and all). If I stop recording, the 45fps sticks, but only for a few seconds, and then I'm back in garbage almost-30 territory. I'm about to try changing my settings back to the recommended Dynamic Medium to see if the results stick.
Why on earth would using the Xbox app's recording stuff suddenly fix things? Could it be the Windows 10 recording overlay that shows up on the screen causing the game to realize it should maybe kind of do its job properly? Anyone else experience this?