This bug was originally marked as duplicate of bug 218370, that is already resolved. This bug is still valid, so this seems to be another bug, but it might be related.
Build: NetBeans IDE 7.4 (Build 201310111528)
VM: OpenJDK 64-Bit Server VM, 24.45-b08, OpenJDK Runtime Environment, 1.7.0_51-b00
GUEST: Downloading maven central index
Maximum slowness yet reported was 65517 ms, average is 65517
Created attachment 145142 [details]
As can be seen from the attached profiler snapshot IDE is waiting for an extremely
slow class loading. Closing as WONTFIX.