For the last couple of days (I think since the latest Chrome update), I've had this issue where the fight speed is inconsistent. Works fine in Firefox, and isn't a permanent problem on Chrome either, but I get it every now and then for some reason I can't figure out.
Basically, the fight speed slows down and speeds up, constantly. Every second or third message in the fight will take a little longer to appear. When I first saw it, it was bad enough to be easily noticeable by just watching the fight, not the timer. Watching the timer proves it - it slows down for 0.2 - 0.4 seconds (on the timer, not necessarily real seconds), and then goes back up to normal speed for about 1.0 - 2.0 on the timer, and loops like that.
It's mostly just an annoyance, but it seems to be either normal speed or slow speed, so it does cause fights to take a little longer.