Setting adaptive to half refresh rate will lock the game to 30 FPS.
Try turning on adaptive V-SYNC in your video cards control panel, as well as triple buffering, set the maximum prerendered frames to 1, and turn on threaded optimization.This looks like a problem with the PC port and should be patched in a future update, meanwhile here are some things you can try to improve your FPS. Some have gone as far as to test the game at 800圆00 resolution with low settings and still their FPS wouldn't improve.
