Eclipse works fine on my Acer Aspire Netbook. I agree it could be better but it's essentially a very capable and adaptable piece of software that's available for free.
IntelliJ is a significantly lesser resource hog. I need 3 gigs with eclipse but only 1 with intellij in ram, and cpu utilization is way better in IntelliJ.
There is something weird with Eclipse on your setup. I just checked mine and it takes 0.5. I normally keep three eclipse instances open (I switch projects and do not care about closing them) and they do not take much memory.