Low fps

I've been experiencing some really low fps for a while now.
It was not like this before, and it goes to unbearably low rates like <10fps.
Any suggestions, please? Playing is unbearable. My pc was fine a few weeks back.

Thanks in advance

Which Realm?
Are you using a client with WoD model?
Try to disable all your addon and see if you still have FPS drop problem

I WAS. I figured that'd be the root of the problem so i got rid of the client, got the one from the website and removed the patch.
and yet...

I play on Neltharion. And even with Razor Cortex, it's hopeless.