I'm trying to switch from opera to Firefox, as title says, Firefox is slow when live commenting is enabled on [http://bilibili.com bilibili.com] when watching videos, it gets worse if you play video in full-screen mode, and CPU is about 15% higher than opera even not in full-screen. I've tested on other two similar website: [http://douyu.com douyu.com] and [http://huya.com huya.com] , turns out the issue is only with bilibili.com, I found that the live comment feature is implemented by canvas on bilibili.com while the other two sites uses css3 instead, and I simply tested canvas benchmark with [http://www.kevs3d.co.uk/dev/canvasmark/ benchmark1] and [https://themaninblue.com/experiment/AnimationBenchmark/canvas/ benchmark2] and the result conforms my guess -- opera performs much better than Firefox. I've tried toggle hardware acceleration and safe mode, no significant improvement observed