In Android 4.1, Google started opening the Google search app no matter what you were doing, which app you were using, etc., as soon as you touch the search button. This is at least the case for my Google Nexus S. Whenever I accidentally hit the button with the little magnification glass, the Google search app opens, instead of the app internal search function. And with 18 Mb, that isn't fun and takes a while. Also it's useless for me.
This is how to disable google search and save your nerves:
1. Go to the settings menu
2. Go to apps
3. Go to all apps
4. Go to Google search
5. Uninstall all updates
6. now the same button shows "disable". Disable the app.
Done! Enjoy! Rejoice ! Relax!
(The app internal search still doesn't work anymore, but at least you save the time and hassle of opening the Google search app.)