Eventual slowdown

[lancelot]

I have two eurosportplayer . com tabs open in a separate browser window, each tab playing a video, one is muted. After a while the tabs become unresponsive, switching between them is slow, and just going in and out of fullscreen mode takes 2-3 seconds. I disable and reenable NoScript, and the issue is gone -- for a while. That makes NoScript nearly unusable for me.

This is in 10.1.5.1, but I think I saw it happen with an earlier version too.