Many of the resources of the IDE and the projects are cached in the browser. If you experience a weird behavior with the IDE or the files, try cleaning the browser cache with the Developers Tools, and refresh the page.
Also, the IDE creates a memory cache of the files of the project. This means, you should keep in the project only the files related to the game, so you keep the memory free of extra, unneeded data.
The best way to clean the memory used by the IDE is by refreshing the browser page.