I have the following basic Titanium Alloy application:
I then monitored the amount of memory the Android emulator was using DDMS, based on the instructions provided here: http://docs.appcelerator.com/platform/latest/#!/guide/Managing_Memory_and_Finding_Leaks
When the application started the number of objects was: 32,188
When I click the button, and then close the new window by pressing back, the number of objects increases to: 32,332
I do this again, it increases to: 32,478
Open and close the window about 8 more times, and it increases to: 34,481
and so on.
The issue is even worse if the window has many objects.
Note I have tested this on both an Android Emulator (Nexus 4) and a real Android device (Samsung S6).
This issues seems to occur on 6.1.X GA
NOTE: I have not yet tested this on iOS yet.