now servers are down, so i'll check later. but if it happens to enyone else please let me know
Had it happen to me a few weeks ago, tried to figure out what it was but couldn't so rolled my UI back a "revision". Meant to post here but the post I wrote got deleted by a computer crash before I could post it and then I got swamped with homework.
Happened again when I mass updated my UI for 2.1, this time I sat down and rebuilt my UI from the ground-up by disabling everything and reenabling in small chunks of 4-5 addons and playing with my mana pool to force regen ticks. I think I've finally narrowed it down to lern2count. Something about the combination of it and its libraries (as of ~05/01, rev. ~34168) is not working out well. Mana ticks lag it (when I switched to my caster gear for the last statue fight in the epic flight form I was stuck at 0.6fps and couldn't move worth anything till my mana pool was full), energy ticks and rage gain do as well, and I think though I'm not certain that health ticks while OOC (natural regen) lag it as well though I didn't check on my warlock.
I can also post my list of add-ons if wanted.