Mac OS can be very slow after being used for long time( e.g. 1 year).. Deep clean right now is not possible without paid software.
Most Mac OS cleaner apps doesn't really boost the performance as much as advertised. I have tried all sorts of existing apps in AppStore, the result wasn't promising.
So I come up with an idea of writing a shell script to do this.
I tried on my own 2 mac, Macbook Pro and Macbook Air, with both running Mac OS X 10.9.3.. Result seems to be exceeding my expectation: 7.5 GB spaces are cleaned, and the system response has been drastically boosted..
Please read and understand this script before using this script. Backup your files via Time Machine if need.
Copy the script to your disk. and execute "sh clean_my_mac.sh"