I ran into the "Juno is ridiculously slow" thing myself (mentioned it just yesterday here: http://news.ycombinator.com/item?id=4488005).

Running Juno on my work laptop (a recent ThinkPad i5 system) is close to unusably slow while 3.8 runs great (for a Java UI-heavy app).

Hopefully this helps sort things out (though donating time of Google engineers might be a better practical solution). In any case, I think I'll stick with Sublime Text 2 for Android development when doing anything other than on-device debugging.