Few days ago I was encouraged by a Mod to review and remove the unneeded comments as a maintenance task.
FYI, and this goes for everyone, if you have spare cycles it would be appreciated if you could go through your list of comments, removing anything that is old or irrelevant. Flag others comments as you go, and we'll get them cleaned up, too.
After a while, I've detected that comments can only by flagged every 5 seconds.
Well, consider a question with a lot of comments, (f.e. 15), you must flag the first, wait 5 seconds, flag the second, wait 5 sec. again, and so on.
It could be interesting to remove this delay, maybe for users with a minimum reputation, or users that got review badges.