I experienced similar problems as well. Post culling patch and running GW2 overheats my CPU pass 70 degrees. Tried cleaning off dust from heat sinks and even had a fan directly blowing onto the motherboard. Problem still persisted.
Solved it tho, i reduced the maximum processor state to 89% (from 100%). I’m running on Windows 7
Control Panel >> System & Security >> Power Options >> Change plan settings (your current power plan) >> Change advanced power settings >> Processor power management >> Maximum processor state
Set it to 89% or lower. I learned this off some forums elsewhere. I can’t pinpoint the exact nature of the problem, but at least these steps will go about it.