Or it just doesn't work right in their browser. It says in big bold letters "VSYNC is not available on the Linux platform" and at 960 pixels per second I actually can't tell the difference between the 100hz and 50hz lines. If I slow it to 480 pixels per second it becomes apparent, but I still feel like that's browser funkiness rather than a true frame rate difference. I don't think it's actually running at 100fps.

It's not my eyes, btw. I can usually tell the difference very easily. I had a problem with my Nvidia drivers for a while that would often make it reset to 60hz on reboot, instead of my display's max of 100. It was always immediately obvious to me just from the mouse cursor, even without consciously looking for it.

LOL as I was writing this, I reloaded the page and now it's very very obvious at 960. Something's definitely inconsistent on my device. Go figure.

I have a 60 Hz monitor and it doesn't even try and display any UFOs above 60 Hz, just 15, 30, and 60. So if they see a row with 144 Hz, then they have a 144 Hz monitor.