I routinely clear the Aurora caches out between EAP's (after getting burned a few times from not doing so during the early ones).
While waiting for the necessary pre-parse of all the Java files and libraries in my project (it's big, but not absurdly so, mostly because of things like weblogic.jar), I started playing with the width of the progress window. Having randomly made it as wide as possible while it was parsing 4,000 or so "input" classes (generated XML wrappers), I noticed that it was taking a LONG time to parse the package, so I shrunk it to as narrow as possible. Having done so, the "outputs" package, which is pretty much equivalent, parsed significantly faster (at least 2x). So, I left the window as narrow as it would let me, and the whole reparse, which has consistently taken 20+ minutes for at least the last 2 months of EAP's, completed in something much nearer to 10 minutes.
Granted, to show that this actually makes a difference, I'd have to clear the caches and time it both ways, but would much rather play with the new EAP today. :) Has anyone noticed anything similar?