It solves the problem, where Firefox writes excessive amounts of data. Even if you disable disk cache. It still stores lot of data. cookies, session storage data...
You might wonder why I made this as an app instead of using Automator or a bash script.
The main advantage of an app is that it displays splash screen with progress, while the RAM disk is being created. With a script based approach, you typically just have to wait a few seconds while the profiles sync in the background before Firefox finally launches. Automator scripts also tend to display an unsightly spinning cogwheel in menu bar, which isn't ideal.
It's MIT licensed and source code is provided.