Juno SR2 brings some performance fixes that was causing heavy lag in responsiveness in the first release of Juno – which made me switch to Sublime for the majority of work.
Whilst PDT worked fine in 4.1, this could not be said of Eclipse classic 4.2 with PDT on top. I’m not sure if this is a common issue, but I eventually found the solution was to install the Eclipse for Java EE Developers edition. This comes with other useful plugins already, so it made my day.