On some sites, like reddit.com, performance is extremely poor. As can be seen in screencast attached, simply scrolling on reddit.com results in extremely low frame rates (like 1-2 fps). I did some more investigation and found that performance on websites that continuously loads images and videos as part of an infinity scroll feed. Another example would be YouTube when loading the thumbnail of recommended videos Firefox handles this just fine. Note: I am not using a touchpad, but Surface Arc Mouse, which still uses steppy scroll.