Mountain Lion Choppy, Jerky, Laggy (Animation)

My newly purchased Macbook Air has choppy animation/transition. I only video record this (Safari), beside this, Mission Control, Launch Pad, etc... are choppy as well. In this video, the transition for opening/closing reading list panel is about 3-5 fps. I 'don't know what's wrong, this is my first macbook in my life and just purchase 3 days ago.

Hardware Info:
Macbook Air 13"
i5 1.8Ghz Dual Core (3rd Generation)
4GB Memory 1600mhz
128GB SSD

OS:
Mountain Lion (10.8.2)

• Category

  • Science & Technology

• License

  • Standard YouTube License