This bug was originally marked as duplicate of bug 223084, 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 (Build 201302132200)
VM: Java HotSpot(TM) 64-Bit Server VM, 20.14-b01-445, Java(TM) SE Runtime Environment, 1.6.0_41-b02-445-11M4107
OS: Mac OS X
GUEST: Was browsing the plugin update list
Maximum slowness yet reported was 21696 ms, average is 21696
Created attachment 134546 [details]
The only once report.