This bug was originally marked as duplicate of bug 171810, that is already resolved. This bug is still valid, so this seems to be another bug, but it might be related.
Build: NetBeans IDE 7.3 Beta 2 (Build 201211062253)
VM: Java HotSpot(TM) 64-Bit Server VM, 19.1-b02-334, Java(TM) SE Runtime Environment, 1.6.0_24-b07-334-10M3326
OS: Mac OS X
jbean: Starting the program
Maximum slowness yet reported was 4657 ms, average is 4657
Created attachment 128096 [details]
Only one report. Was the UI responsiveness issue really a problem for you?