I was having a bunch of hard to explain FPS issues, that were intermittent, but would persist through game restarts.
It turns out they were all caused because of Yolomouse.
I only installed it because these forums recommended it as a solution to the hard to see pointer. DO NOT use Yolomouse.
You can go into windows settings and make your cursor bigger system wide. This will unfortunately make it huge in your desktop, and it’'ll still be a dim color, but its better, and will cause no fps issues.