This is easily the most annoying timer on the site: post a second comment too quickly after the first, and the system kicks it back, telling you to wait 15 seconds. Count to 15 too quickly and retry, and it'll reset the timer...
Ok, I get it, we really shouldn't be posting comments that quickly. But for a moderator trying to respond to flags in a polite but expedient manner, this is an unnecessary hassle.
Remove the comment rate-limiting entirely for moderators. If your moderator is posting trash comments, you probably have bigger problems.
Restrict it to rate-limiting comments on a single post. That is, trying to rapid-fire comment on one answer fails, but posting one comment to one answer and another to another go through without a wait.
Get rid of the infuriating timer reset. Ok, fine, gotta wait 15 seconds. It probably took me 14 seconds to get to this point anyway, so big deal. But come on, why do I have to stare at this infernal button for another 15 seconds?