Abstractions are awesome. But when you tune for performance, the abstractions break down.
This is not inherent, as abstractions could have fully specified the performance characteristics of their primitives. However, most don't, so to get great performance out of your tools, you typically have to see directly through the abstraction layers.
When you write a quicksort algorithm, it is pretty important that you know about cache lines and the relative costs, or your quicksort will not be nearly as good as the one that does take that into consideration.
This is not inherent, as abstractions could have fully specified the performance characteristics of their primitives. However, most don't, so to get great performance out of your tools, you typically have to see directly through the abstraction layers.
When you write a quicksort algorithm, it is pretty important that you know about cache lines and the relative costs, or your quicksort will not be nearly as good as the one that does take that into consideration.