Having been confused by this myself I’ve also seen the same confusion elsewhere. One criticism being that Compiz slows down productivity and is only “eye candy” because it hogs the system and slows things down. This does not have to be the case and Compiz already has a mechanism built in to manage what is a valid criticism.
In “CompizConfig Settings Manager” go to Preferences (bottom left of window). You should be on the “Profile and Backend” tab. You can create and remove profiles using the plus and minus buttons. On my system I had to use the Flat File backend as GConf did not seem to save the profiles, although that just may be something to do with my system. Don’t worry about not having Desktop Integration. At least with my usage I noticed no difference. Anyway, GConf may work for you so you may have it.
So now test the profiles. Switch between two of them with known settings and go back to the main window and check the plugins are being turned on and off. Working ? Good.
With that functional you can now create uber system hogging Compiz vs pick and choose Compiz. I created a “Zoom only” profile because I find the very fast enhanced zoom useful on my desktop. With only the most minimal plugins and effects turned on for my desktop it is almost as fast as when Compiz is turned off (this is on a medium end AMD Sempron 3000+ CPU and Nvidia FX5200). Another profile has some of the more flashy but slightly system hogging effects turned on for when I don’t mind if the desktop slows a little.
No doubt there are other combinations of the more production enhancing plugins that can be enabled using profiles that do not hog the system and allow the enhanced GUI management features to be used to their full effect.
So that’s the end of my Compiz blog post. I hope it allows more people to properly tune Compiz. Like any piece of hot technology … like a fine car .. it needs looking after !