Netbeans Profiler Milestone 6 now supports JDK 5.0 and the Mustang builds and contains some performance improvements.
Sorry that I’m a bit late, I just read it in the Javalobby newsletter. 
According to the docs, it doesn’t support JDK1.5 yet (we’ll have to wait until june and an 1.5.0_04 release), but is said to work well on 1.6.
Lilian