I have had the issue before .....but only when my cpu clocks itself down. Sometime my cpu goes into a low power mode, which downclocks my multiplier on my cpu by 50%, reesulting in 1.6ghz compared to 3.2 and that can cause the game and everything else to come to a halt or just lag. Id suggest downloading cpu-z and look at your cpu activity there and see if this is the case for you. If it is, i suggest going into bios and diaabling all cpu power saving features, and going into your windows control panel and configuring your power options to full power so your cpu doesnt go into idle or power saving mode.