What can cause spell and chat lag?

[Lhancelot]

Just curious what can cause this. I am pretty sure it's on my side of things.

I have ran antivirus programs, I am not running anything behind the game, etc., but every day for the last week or so, I get this crazy spell/chat lag. it's intermittent.

It will hit for an hour or so, then just disappear, and might come back later on too. Anyone ever have this issue, and figured out what was causing it for them?