After clean boot with only Chrome running idle, Compiz is taking 25% all the time. It keeps my fan running non stop. Is this a regression or something?
As @Pisu stated, this is now a bug on launchpad.
I was having the same issues. This thanks to the PPA of Daniël van Vugt, compiz CPU usage dropped from 40% avg to 5% avg, also GPU temperature dropped about 15°C when idle, and a drop of about 30°C (!) when stressed.
However, the PPA is still experimental and for me it creates flickering when switching workspaces at the moment. The fix is being worked on and it will land in the normal updates if you have enough of patient (more than a month is possible I guess)
Please test my PPAs which contain proposed performance enhancements for compiz and unity. Generally the Unity plugin is the largest contributor to compiz' CPU...
ppa:vanvugt/compiz | https://launchpad.net/~vanvugt/+archive/compiz
ppa:vanvugt/unity | https://launchpad.net/~vanvugt/+archive/unity