Using the session to store runtime behaviour is not ideal, because it will always start the session for the user and disable the Contao cache. Since the properties seem only used for the current request, we don't need the session to transport them to the next page view.
I have updated some of the places that should affect the front end. There is also a lot of session usage in the DCA callbacks, but I couldn't figure out how that is used (it is only read but never set…?). It shouldn't affect the frontend though.
Using the session to store runtime behaviour is not ideal, because it will always start the session for the user and disable the Contao cache. Since the properties seem only used for the current request, we don't need the session to transport them to the next page view.
I have updated some of the places that should affect the front end. There is also a lot of session usage in the DCA callbacks, but I couldn't figure out how that is used (it is only read but never set…?). It shouldn't affect the frontend though.