Framerate died

[casht0wn]

So I was playing for a couple hours (no issues) and noticed I could get OEM bikes so I downloaded the pack and installed it (again, without any issues) but now I get only about 2 fps.

It doesn't seem graphics-related because CPU and GPU usage are really low (<20%) and it's just as bad even if I set all graphics settings to min. Oddly, I can get up to about 17 fps if I set it to 1440p, but that's the best I can do. It's seriously unplayable now.

I only have an R9 290 but I was playing fine at 1440p for a few hours. What could suddenly cause this sort of crap performance? Is it the bikes themselves? Should I just reinstall the game and avoid the OEM bikes? Would that even help? Anyone ever seen/experienced this issue?

[Snappe]

If you use stock bike and track, does fps go back to normal?