JEmu2? Others? The smaller and more self-contained the test case the better.
I'll see what I can do.
As for JEmu2, it basically runs fine with -Xprof, except for the Swing front-end: If I run it with front-end, it basically halts when drawing the GUI (it doesn't get beyond drawing an empty, grey, unresponsive JFrame). If I run the emulator without front-end, it runs close to full-speed. Without front-end, no Swing is used, so using Swing or AWT seems to trigger the problem in my case.