I just tried it on an iPad Pro with Safari. Clicking the tiles does not work, scrolling does not work with the touchpad, and overall it feels very janky. They probably didn‘t care to optimize / make it usable with Safari.
Trying it on Windows 10 with Firefox. Scrolling is incredibly slow, in every possible way. The scroll wheel barely moves the content, so I have to spin the wheel ten or more times to get any reasonable distance down the page, and the animation is janky and stuttery.
I remember getting accurate values from the scroll wheel being the worst in Firefox and basically impossible. You could only get the scroll direction, but not the correct extent (bascially everything just looked like one detent). So you either get incredibly fast scrolling, or incrediby slow scrolling, depending on how you work with the value and whether you still do the oft-needed division by 120. This can also make some touch pads that generate mouse wheel events very unusable for zooming or scrolling.
The scaling there works with very different speeds in Firefox and Chrome because both disagree on what value the delta should have. Scrolling up once yields -100 in Edgeium for me and -3 in Firefox.
Works great in Chrome though, what a surprise!