Probably the most wild example of the server delay (not even latency, just the servers being slow) is that I can run a couple constant pings. One to google.com, which will be pretty constantly at 15ms, and then one to the datacenters at about 100ms. (The hop into Canada goes from 15ms to 85ms, then up from there). So 100ms to the servers. I can be auto running and cast Leeches on myself (1.0 sec cast, or 0.97 with some spell speed). Client side I can actually have the animation go off (no battle message because server side it really never happens of course), but what this tells me is that 100ms is accounted for in latency, and another 800-900ms is lost in the server taking time to process the fact that I'm moving and the spell needs to be interrupted, and send that back to my client.

I wish they would at least say "This is an issue, we're stumped on how to fix it, but we're looking into it."