On Firefox for Windows the touch and pen logic is a mess. When I hover over something with the pen or scroll using touch, Firefox seems to make both elements hover and triggers even JavaScript related code at very high rate. These 2 elements are where the real mouse/cursor is on the screen and where the currently touching or hovering over element is. For example rest your mouse on the YouTube HTML5 player, then use a pen to hover over the browsers close button or even just something else on the web page like the like button. This will ramp up the CPU and make both the player and the like button your are hovering flicker between ::hover and ::normal. This will also call lot's of instances of these related events in the website's JavaScript. Another semi-related issue is when using the F12 developer tools in "Device Simulation" mode, It's impossible to for some reason because Firefox fakes real touch injections into the OS (and they show up as if I touched the screen by the OS) which cancels the precision touchpad input movement until I lift my finger from the touchpad. This is specifically a "Windows Precision Touchpad" issue, and There is no known fix to this apart from not using a such a touchpad... On old 10+ year old laptops with PS/2 or proprietary Touchpads that report themselves as a normal Mouse this issue won't occour but Firefox will still input system-wide touch input. As a developer myself this seems very silly because you own the source code and could solve this way more elegantly than asking the OS to input Touch events... Let me know if you need anything else, and point me out where the source for the input (specifically for touch and pen) live so I can take a look at it and make some improvements. Thanks