Today I noticed the game was much slower than just one or two days ago. Then I checked Switch Web Mode and: there is only one UJS option left and I guess it is UJS-Canvas. For most people that may be fine, I guess with the right setup of modern browser and fairly modern hardware it works flawlessly.
But I have an old laptop from 2010 which I still use a lot and it it has some crappy old generation Intel HD graphics chipset. I assume that's why canvas isn't properly hardware accelerated in my browser, the other UJS version worked much better.
@Fizzer: it wouldn't be much hassle to leave both UJS versions as a choice with canvas as default, would it?
UJS-Canvas default now? too bad..: 1/20/2019 00:08:34