Neverwinter Online - How to configure and set refresh rate and max fps
FOR NVIDIA USERS -IGNORE VID AND JUST DO THE FOLLOWING: Press ALT + ENTER in the character select screen 1 to 3 times or until it adjust back to fullscreen. Lag problem solved. Not even kidding.
My GTX 970 no longer had excessive lag in Strongholds and practically everywhere else after I did this. Hope it helps.