Big lag bursts when casting, but with no latency

I've been having this problem on and off probably forever, but lately it is especially bad in battlegrounds and devastating in arenas. Usually happens when I start casting, or pop a couple cooldowns and try to hit my instants - I get a 2+ second lag spike before anything happens. I also see the spike a lot when I get a kill, or get close - I see the spells cast, I see them connect, health bar doesn't move, 3 seconds later - player appears to be dead.

I have been looking at my latency during these spikes and it stays <90ms on all 4 clients.

I'm software boxing, keyclone on a quad core 2.66ghz with 8GB ram. Cable internet, ~6mbps down 1mbps or so up, going through wireless.

Anyone else having this problem?

I'm gonna point to some phantom addon. Disable every addon and see if it happens.

Some of it might be server latency.

Try not to run arena, during Wintergrasp.
If you're getting it, but they're not, or it occurs in other area's and at other times...

Not really sure, beyond the previous replies.

try reducing yer graphics settings a lil. LIke kill shadows and spell afffects.

The ping you see in the wow client is an average over like 3 minutes. So you may be getting spikes up to 3000ms or so without actually completely lowering your average.

I've been seeing this lately too. WG is not running and spell casts will be bad for 5 minutes and then fine. Not sure what is going on, but I just attributed it to random net traffic.

run ctrl+R to make sure this is lag and not low framerate... if it's the latter then reduce particle density first (since it's happening with spells) and see if that helps anything. If you get a constant good framerate... then you're getting lag spikes. If you run recount they have a realtime latency graph you can run just to be sure.. but... if it's not framerate there's nothing else it can be... check with your ISP and figure out what's going on. Switch if necessary.

well I always have the fps on and it's definitely not the source of the problem. /shrug