Editor Notification
You may see notifications like these in the top-right corner of the source code editors:

They show up when DVT automatically detects issues with your project, such as:
a huge number of files and directories or a slow filesystem, which may lead to Eclipse Platform slow-downs, see DVT Resource Monitor
changes in the code or project configuration which cannot be handled incrementally, leading to an out of sync database, see Incremental Compilation
Click the “+” on the left for more details:

Hover the button on the right to see the proposed fixing action:

Click the right button to trigger the operation.
Note
The fixing operation might be computationally intensive (for example a project rebuild) or might have a significant impact on the resources from the workspace.