I'm reading a number of sites on making ubuntu faster/more lightweight (e.g. this guide, and many mention replacing Metacity with Openbox. However, in 12.04 on an Inspiron e1405, I only see Metacity taking 11MiB and (fairly consistently) 0% CPU. Am I missing something? Seems like I would be optimizing zero to replace something that uses that few resources
About metacity, I love it very much because of the Ambiance theme. But if compared to openbox, I have to admit that it is quite heavy. Openbox uses only 6.6MB of RAM with 0% CPU on my laptop. So, if you are going for speed, give openbox a try.