Comment by galangalalgol

You aren't the target audience I think? The main two reasons to use custom alloctors, or the two I run into at least, is when memory allocation profiles as a significant portion of your flamegraph, and/or there is a real probability of memory fragmentation preventing new allocation even when there is plenty of space left. That latter is often the case with embedded. The former can be, and is also pretty common any time you are cpu bound as in gaming or signal processing.