Lately I am experiencing this strange game not responding. Screen just freezes and WoW stops responding. Not DC, not lag, just stops responding. This is happening in Arena always. Never happens outside arena.
My PC is quite powerful and I am running on 100-300 FPS. Why do I still get this ?
It might be related to some addon you might be using, if you are using any. I would start by disabling your pvp related addons and start enable them one by one and test your performance.
As a general rule i always delete Cache and WTF once my game starts getting cranky:
Deleting those folders is in essence restoring the game to a "first run" status, where as far as the client is considered it was never run before. People do this to resolve errors that come up on the client or add-ons.