Fix for bad performance in Eclipse Juno SR1

Several major performance defects have been addressed in the Juno SR2 stream (4.2.2). Community members have confirmed that these fixes substantially address the performance problems with editor and view opening, closing, and switching. These fixes will be widely available in the Juno Service Release 2 (February 2013) and Kepler (June 2013) releases. Meanwhile, a patch is available for those using Juno SR1 that provides early access to these fixes. To install this patch:

1. Ensure you are already running on a package from the Juno SR1 release (September 2012)
2. Invoke Help > Install New Software
3. Select this repository: http://download.eclipse.org/eclipse/updates/4.2
4. Expand Juno SR1 Patches and install Eclipse UI Juno SR1 Optimizations

Source: 
http://wiki.eclipse.org/Platform_UI/Juno_Performance_Investigation

Hope this helps someone