My list of things that help
This happens to me when I load a char in LA.
1 . load a char who is not in LA
2. on my desktop I have a gw2 shortcut. Right click it and select properties. on target line add this in front of before what you have there C:\Windows\System32\cmd.exe /C START “GW2” /affinity 55 and make sure there a space after 55
This issue started for me when dragon bash started. When I updated my Nvidia drivers I received a message that physx driver was not installed because there was a newer version on the machine.
Things I tried. CPU, Gpu and PS are not overheating and a waste of time to explore when its GW2 that is the only time ( game) that causes this issue.