Im finding after a few weeks of GWT development my Development Mode compilations suddenly slow down at the stage where you see this in the Development Mode console log:

```
Validating newly compiled units

```

I've found a related question but this seemed a little vague compared to my issue

[Eclipse getting too slow - workspace recreation helped](https://stackoverflow.com/questions/4386119/eclipse-getting-too-slow-workspace-recreation-helped)

Since I lose window/toolbar layout settings (even if export/import prefs) and other useful things when I recreate the workspace I want to find out which files I can clean?

I've [raised a bug](http://code.google.com/p/google-web-toolkit/issues/detail?id=7036&can=4&colspec=ID%20Type%20Status%20Owner%20Milestone%20Summary%20Stars) with GWT..