Lag associated with combat actions

I'm on a Mac running OS X 10.7, and I seem to be experiencing an issue with lag between the time I click the left or right mouse button in combat and the subsequent spell/loot action taking place. The character animation happens immediately, but the action itself does not.

Here's an example. My character is using a wand, and when I click the left mouse button to fire the wand, my character raises the weapon and points it, and then returns back to a stationary position. About 10 seconds later, I see the spell shoot across the screen and strike the target. The same thing seems to be happening for looting bodies, as well.

Hope that provides enough detail to help!