Lag occurs 24/7... for about last month every day... regardless of action... be it moving on the map, trying to enter arena or search auction house, compose a pot or extract a resource.... or anything else you can think of. Only thing that is consistant, is that if lag doesnt spike for ~20...40 seconds, it goes bad or even worse for the next ~30...60 seconds (page load times from 5...15 seconds during that time)... and then the cycle repeats itself... over and over... every day, every hour, every minute... please figure it out and find a solution.
That pretty much sums it up - doesn't matter what you're doing, you can be fine, then spike and continue to repeat indefinitely..