This bug was originally marked as duplicate of bug 194969, that is already resolved. This bug is still valid, so this seems to be another bug, but it might be related.
Build: NetBeans IDE Dev (Build 20120112-e45189fc0316)
VM: Java HotSpot(TM) 64-Bit Server VM, 20.4-b02, Java(TM) SE Runtime Environment, 1.6.0_29-b11
Maximum slowness yet reported was 3357 ms, average is 3357
Created attachment 115397 [details]
Code Completion thread is blocked by an extremely slow IO (java.io.UnixFileSystem.getBooleanAttributes(File)).