Counter Strike Global Offensive runs a little slow

I installed Counter-Strike Global Offensive on my MacBook. It works but sometimes it's running a little bit slow (freezing, lagging).

The specs on my computer:

• 2.4 GHz Intel Core 2 Duo
• 4GB RAM
• NVIDIA GeForce 9400M 256 MB

I turned all the video settings I could find in the game menu to the lowest option possible.

Is there anything else I can do to make the game run smoother? Maybe change some advanced setting from the console?