Kepler is coming and it have many improvements performance wise over Juno and is the only version certified to run on Windows 8 afaics. It is also the first version where WTP static web project becomes more usable. and of course the general notion that Kepler is the only version we can actually get fixes into.
Migration guide for Eclipse Platform (currently empty - I've posted question on http://dev.eclipse.org/mhonarc/lists/eclipse-dev/ to check if better new doc)
Migration tips for WTP (this time there are Actual changes!)
Please link related Kepler runtime/build issues to this issue.