This bug was originally marked as duplicate of bug 251825, that is already resolved. This bug is still valid, so this seems to be another bug, but it might be related.
Build: NetBeans IDE 8.1 Beta (Build 201508041349)
VM: Java HotSpot(TM) 64-Bit Server VM, 25.51-b03, Java(TM) SE Runtime Environment, 1.8.0_51-b16
OS: Windows 7
Lolo_101: Normal java code edition... 39 open maven projects.
Maximum slowness yet reported was 5877 ms, average is 5877
Created attachment 155452 [details]
As can be seen from the attach profiler snapshot - all IDE activity seems to be blocked by an extremely slow IO (usually java.io.WinNTFileSystem.list).