As always, there's a spectrum of problems that require increasingly lower level grunt work to be fast "enough" (or rather, "performant", as The Management likes

As always, there's a spectrum of problems that require increasingly lower level grunt work to be fast "enough" (or rather, "performant", as The Management likes to say these days) However, to me at least, it makes sense to start at the top and work your way down when bottlenecks arise (systems level software aside): Configuration -> DSL -> scripting -> "FP on VM" -> "(mutable) OOP on VM" -> "traditional 3GL (with bounds checking)" -> C -> assembler -> hardware. Generational GC should take most of the pain out of immutable temp value churn. You can also use libraries and frameworks that "ask nicely" to mutate things, such as behind-the-scenes internal accumulators for filter/map/reduce type operations.