You don't need profiler feedback for these things, just back-of-the-envelope calculations. How much data you would like to store and process is not something a profiler can answer for you.

I can tell you that in one of my programs, the difference between garbage collected strings and optimized ones (actually, strings converted into unique integer handles immediately) for one of my projects (SAT solver in Java), handling a few million variables, was something like a second until completion vs a couple of minutes before the garbage collector finally dies due to lack of oxygen, losing all data computed up to that point.