When a developer swaps out of the IDE to another project/program/debug/etc..., the only files NetBeans really needs to immediately know about with regards to changes are the files which are opened in the IDE.
Any additional files will be refreshed/updated upon opening in the editor, building with Ant, running, debugging, etc...
At present, within the 6.9.1 IDE, I have 10 projects open. 7 JAR projects. 2 EAR Projects, and 1 JavaFX Project. The only file I have open is the main frame/stage file for the JavaFX Project.
When I swap out to check EMail or IM and return to the IDE, the system immediately starts checking all 9850+ files in the 10 projects (about 5 minutes processing time). During this check, the compilation/debugging of the JavaFX file is delayed due to either a lack of resources (like CPU hogging), or a block until the process is completed.
The check needs to happen in 2 phases.
Phase 1 is to check the open files. This needs to be quick and should be doable for the limited number of files NetBeans can hold open in a matter of seconds.
Phase 2 is to check the closed files. At present, the only reason I can envision doing this is to update any icon flags for revision control or similar reasons. This should be run at a lower priority in the background.
[In response to next question, sorry but I cannot provide the large project files]
Actually the currently selected file and its folder is check first. Anyway because of bug 26230 being finally handled, I don't think we will need to implement this enhancement anyway.