Mac problems

[Hulikner]

Hey guys.
I have been playing wow for a month and I have an issue I cant fix.
I have a MacBook pro and when I play by my self I have no problems at all.
When my brother gets on and we are playing together, I lag so bad in combat it's unplayable. But the thing is, he never ever gets lag. I know I'm new to wow so I figured that I may be missing something.

I've tried what WoW GMs suggest of deleting certain folders and running repair. No luck. Also, I have 0 addons.

Please help.


Btw my brother has a new windows computer and I have the new MacBook pro. We have recently bought a new router also. I don't know the computer specs off the top of my head but I don't think that will matter anyways. Seems to be a Mac issue.

Thanks