This bug was originally marked as duplicate of bug 171183, 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 201206140001)
VM: Java HotSpot(TM) Client VM, 23.1-b03, Java(TM) SE Runtime Environment, 1.7.0_05-b05
Maximum slowness yet reported was 2062 ms, average is 2062
Created attachment 120850 [details]
As can be seen from the attached snapshots, code completion is waiting for an extremely slow IO.
Created attachment 121146 [details]
Editing java source code.