>>> My Info: Win7_64, Nightly 49, 32bit, ID 20160526082509 STR_1: 1. Disable HWA, restart the browser 2. Open http://js1k.com/2014-dragons/demo/1670 3. Enable HWA, restart the browser 4. Open http://js1k.com/2014-dragons/demo/1670 AR: Step 2 - The demo is not smooth, it's more laggy on Firefox than on GoogleChrome Step 4 - The demo is unimaginably more laggy on Firefox with HWA enabled than on GoogleChrome ER: Either X or Y or X+Y X) Step 2 - the demo should be smooth Y) Step 4 - the demo should be smooth Note: It seems that the accurate description is "This js1k demo is more laggy on Firefox, way more laggy with e10s/apz enabled, unimaginably more laggy with HWA enabled", but I had not time to check e10s/apz thing. You do this. Also, bump this bug, and I'll attach troubleshooting data (currently I have no means to do that)
User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:50.0) Gecko/20100101 Firefox/50.0 Firefox 50.1.0, Build ID: 20161208153507 I have managed to reproduce this issue on the latest Firefox (50.1.0) release and latest Nightly (53.0a1) build with hardware acceleration on. The animation is pretty leggy. The issue in not reproducible if I disable the hardware acceleration, the animation is smooth.