Random Severe FPS drops that won't go away.

Hello all!

My friend is having a rather large problem right now. Randomly when he's just exploring the world and questing, his game will slow to a crawl (going from 50 FPS to 5 FPS). Cutscenes are fine, and most instances act normally as well. However, after getting back into the main world, it's back to going 5 FPS all the time. *Sometimes* restarting the game will fix it, other times not. And we all know how risky it is to restart your game right now with all the server issues. :P

Anyways, he has a good computer and can play the game at max specs going around 50+fps all the time. Except when this problem happens.

He has a NVIDIA GTX 460.

Any suggestions as to what is causing this?

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I have a separate, although similar problem. Sometimes my game will be working fine, then suddenly, my FPS will go from 50+ to 5, and immediately crash my game. I've noticed that one of the big trigger factors is the teleporting animation. Most of the time when this happens, it's immediately after the casting animation for teleporting starts. Not sure what is causing this. I have a Radeon HD 7870.

We both have up to date video drivers.

Any help would be appreciated! Thanks. :)