Most recent Ubuntu 12.04 seems to be quite nice and Unity (3D/2D) works fine for me, however not on my old Acer Aspire One any more.
There was a times, when I switched from Windows XP to Ubuntu and was happy about system looks, effects and speed... now I attend to think that XP was really great comparing with 12.04.
I have found similar questions here but no reasonable answer: how to lower CPU usage for Unity (3D/2D) and memory consumption for Ubuntu 12.04.
With new interface I could not find how to disable background services...
It's Linux, it's should be the way to optimize without buying new PC... Please share your recipe!