I asked this question already on Askubuntu, but was directed to file a bug: I have a nice Lenovo Thinkpad Edge 11 AMD Neo II with a ATI Radeon 4225 integrated graphics device. In my perception this is already a not-so-lowspeced device, but still a netbook.
Up to Ubuntu 12.04 precise pangolin I preferred Unity2D over Unity mainly because it did perform much better than Unity and moreover I was able to achieve 5-6h with one battery charge. The typical load of an idling desktop settled around 0.00 to 0.02.
Yesterday I tried the new Beta 2 of Ubuntu Quantal Quetzal: This does no longer offer a Unity2D version. The performance itself has definitely improved over Unity in precise, but nevertheless I do experience now a minimum load of 0.24 to 0.36 while completely idling. According to top this is mainly due to compiz eating about 3-6% CPU all the time.
In comparison to my Unity2D experience, quantal is more sluggish, eats much faster my battery and produces significant more fan noise. I already tried a few tweaks like static blurring, fast texture renderer or choosing alternate window manager on precise, but without a significant change.
Are there ways which enable me to continue to use Ubuntu/Unity on my device without major loss of functionality, performance and battery life?
DistroRelease: Ubuntu 12.10
Package: unity 6.8.0-0ubuntu2
ProcVersionSignature: Ubuntu 3.5.0-18.29-generic 3.5.7
Tags: quantal running-unity
Uname: Linux 3.5.0-18-generic i686
UpgradeStatus: Upgraded to quantal on 2012-11-06 (0 days ago)
UserGroups: adm admin audio cdrom floppy fuse kvm lpadmin netdev plugdev tape video