Use "Adaptive" or turn it off in-game and "On" in the control panel.
Turn this Off if you are using an external limiter like RTSS or NVIDIA's control panel. Guide :: Assassin's Creed II Stuttering and Performance Fix Assassin's Creed 2 - How to Boost Fps, Fix Stut...
Right-click the game .exe , go to Properties > Compatibility , and check "Disable fullscreen optimizations." 5. In-Game Settings for Low-End PCs Use "Adaptive" or turn it off in-game and