http://forums.ageofconan.com/showthread.php?t=36047According to this link, if you're experiencing FPS issues DON'T set your game to "Low". Apparently there is a bug that causes the game to perform worse at these settings.
Supposedly if you set everything to High and then turn Shadows (and possibly water reflections off) then you'll find you have better frame rate. Plus the game looks gorgeous.
I haven't tried it myself, but Jalarn has and says it's working.