Indeed, if Netbeans is 'lightweight' then E texteditor or notepad++ must be hardware accelerated by a dedicated chip :D. Netbeans has to be one of the slowest and most resource consuming IDE's I ever used.
To be fair, E and notepad++ are not IDEs. IDEs are much more than syntax highlighting. And Netbeans has been working hard to improve performance. 6.9 Beta was released, and the Dev releases before that were doing better then 6.8 and earlier releases in the memory arena.
It also depends on which "flavour" of Netbeans you use. Netbeans for Ruby (i.e., without the Java stuff) is really very responsive (although I don't need/use code completion).
A bit of scouring around and I found some configuration settings to speed up Netbeans's garbage collection & buffers. Made it pretty snappy on my mac. Now that's once it's loaded and I'm editing; other times can still be slow.
But it was a happy switch from Eclipse. Netbeans took longer to do things, but it didn't require that I try doing them 3-4 times before anything would happen (e.g. start/restart tomcat).
