Is there a simple way to enable/disable groups of fonts? I mostly works with Photoshop and Coda (programming app). I have installed many fonts and at the time I work with Photoshop I need all my fonts enabled. 

But then after I don't need all the font but only the default system fonts.

Problem is that these font are slowing down my machine.

Can I create groups of fonts and then enable/disable these groups?
You can create font collections in OS X's own Font Book. These collections are shown in the left column and can be activated and deactivated from the context menu (right click on a collection name).

Fonts can exist in multiple collections, so you could create one with all fonts to be deactivated after your Photoshop work, but also more differentiated and overlapping groups if needed.