i was having this problem and found this and so far it seems to be helping:
1: Right-click your gw2.exe and choose Properties.
2: Go to the Compatibility tab.
3: Under Settings check-mark ’Disable display scaling on high DPI settings
This worked for me. Before, I could only go 3-5 seconds before my character would stop running while holding down both buttons, now she runs smoothly, and right camera turning is golden too. THANK YOU. Huge turn off when just starting this game, Anet should really get on top of this.