The extension does not do anything with your mouse, nor does it make any actions delayed, because it simply doesn't activate itself until the video on a webpage is in fullscreen mode. Once you go out of fullscreen, it destructs itself.

Kindly try new version and let me know. It could be that in the past v2 keyboard shortcuts feature may have introduced some lag, but in v3 and upwards that's no longer the case and possibility, because it uses browser built-in commands feature.

Please test again and I'd highly suggest you to use incognito (and allow only ultrawideo in incognito) to make sure that it's not some other extension that interfered with UltraWideo, making your actions have input lag.

Kind regards!