To be honest I don't know either. Eclipse has always runned fine until the rare day when some plugin goes overboard and destroys all hope.

Last year for instance I've had bad issues with autocompletion on some huge classes (GLES20 I'm looking at you), but 1) that was when I was struggling on the macbook already, and 2) Someone fixed the problem somehow while I was busy downgrading to a stable version.

Eclipse kicks ass. I only said it was laggy out of mercy for the people who can't get productive with it.