[deathanatos]

… that's really not the idea I'm trying to convey with the comment.

Clearly, if you feed a program a larger file that it is going to read into memory to process, it is then expected that it will consume more resources on account of it doing more work. But that is memory being expended on visible, useful work. All of the examples in the comment are referring to memory being "allocated" (in the sense of being assigned to the program) but not fulfilling any visibly useful function insofar as the operator/programmer can see: Java's GC being unable to effectively reclaim unused memory prior to killing a machine, the OP's example of a Vec allocating without (seemingly) have a purpose (…as it is excess of what is required to allow for amortized appends).