Why does my mouse run slower in Firefox than on the desktop and other apps?

Windows 11 desktop - latest version with previews. Within the last week or so, my mouse has started moving very slowly within Firefox. I've tried refreshing and reinstalling Firefox (which is up to date) and deactivating all extensions. However, this makes no difference. If this can't be fixed, I will seriously consider using another browser as my default in Windows (long time Firefox user).