You're so far away from the hardware when you're in an interpreted environment, reasoning about performance is fraught with danger. Happy paths could be an orde

You're so far away from the hardware when you're in an interpreted environment, reasoning about performance is fraught with danger. Happy paths could be an order of magnitude faster than very similar but just different enough code. Usually, in an interpreted environment, I reason about other things: number of database calls, HTTP fetches, that kind of thing. If I need CPU performance, I'll fire up something faster. Finding the meatiest primitive that does the job in one go is often best - batching, where the batch operation is implemented in native code - but not always, you're at the mercy of the implementer.