What's your PC specs? RAM, graphics card etc. I use a 60Hz refresh rate on my monitor, and my CCD runs perfectly, 60FPS on a 60Hz monitor. Frame rate never drops. My specs:
CPU: Intel Core i7 2600k overclocked @4.4GHz
RAM: 8GB RAM (2x 4GB sticks)
Graphics Card: Dual videocard (SLI) Nvidia GTX670
Motherboard: Asus P8Z68-M Pro