copy and paste this: http://www.youtube.com/watch?v=gDA-awmYTNU
That is one of the worst lag spikes i've gotten. Lag spikes happen serveral times in a minute and its not my router/firewall because I allowed my IP through DMZ temporarily for this test. It also is not slow computer performance as you can see my frames are just under a 1000 and I have no problems in Single player .