scaling...the other way

Ignoring the engineering of a huge app the answer is simple: one app
always uses fewer resources than the equivalent functionality split up
into many small apps. Mostly you'd just be using less RAM.

Whether or not to separate the functionality into multiple apps would
depend on the nature of the functionality (if you want to have a
single login for instance, than it should probably all be in one app).
The resource usage would be very low on my list of considerations.