I'm experiencing a bug where performance in the drawing window drops drastically when using a mouse with a faster polling rate. I made a screen recording demonstrating this issue here.

Some things to note from the video:
- First, I show that using a brush works fine with the mouse set to 250Hz
- Next, I show that using a brush is slow/impossible with the mouse set to 1000Hz
- The last bit shows that using a pen tablet (Huion H58L) works fine regardless.

Not that weird... If you mouse sends more events, then Krita has to do more work. You are sending 4 times as many events to Krita, and for every mouse event, the brush engine has to do work.

It's just inconvenient to have to switch between polling rates when I want to use Krita after playing a game. It adds a noticeable amount of latency to cursor movement. Oh well, if there's not much that can be done about it then I have no choice.