This bug was originally marked as duplicate of bug 192317, that is already resolved. This bug is still valid, so this seems to be another bug, but it might be related.
Build: NetBeans IDE 7.2 Beta (Build 201205031832)
VM: Java HotSpot(TM) 64-Bit Server VM, 23.0-b21, Java(TM) SE Runtime Environment, 1.7.0_04-b22
OS: Windows 7
GUEST: I selected 32 small image files from windows file system and dragged them to a folder in my project in netbeans. I stalled.
Maximum slowness yet reported was 17870 ms, average is 17870
Created attachment 121415 [details]
Blocked in call to
sun.awt.windows.WDropTargetContextPeer.getData[native]() 99.9437 17 736 ms (99,9%) 17 736 ms
I don't think there is anything we can do about that.