My screen freezes for a second anytime I'm in a group

[JuJubean]

Hey I'm having some issues anytime I'm in a group out in the world and in a dung where my screen freezes at the moment we kill a mob. It freezes for like a second. Doesn't happen when I am solo questing, just when in a group. It's only happening on the Onyxia server. No troubles on Lorderon or Icecrown servers. Any suggestions?

[Mitzen]

Disable all addons. Does it continue? If it doesn't, enable addons in batches to find one causing it.