It's sad that this question hasn't actually even been answered yet. Some things perl does under the hood to be fast are that integers are (mostly) actually int

It's sad that this question hasn't actually even been answered yet. Some things perl does under the hood to be fast are that integers are (mostly) actually integers under the hood. Arrays are actually arrays under the hood (a fact that makes perl's DBI very fast). And more importantly it has had decades of people trying to make it faster without changing the (sometimes crazy) semantics of the language. But of course languages with JITs a have massively overtaken it in the performance stakes (PyPy, LuaJIT, and JavaScript). Mostly I think this is a result of lack of funding and huge company spending. Just look at what Facebook have managed to do with PHP.