Custom allocators are quite common, it's not an arcane convention. I think the rule of thumb is preallocate until it gets questionable in complexity, then write

Custom allocators are quite common, it's not an arcane convention. I think the rule of thumb is preallocate until it gets questionable in complexity, then write your custom allocator - and really it's only applicable to code with a real-time deadline (hard or soft). Otherwise the system allocator is going to be a lot smarter than yours once it leaves microbenchmarks.