I agree that all those pieces are important, for sure. But it can all be undercut by a few for-loops that don't consider string re-allocations. That covers the

I agree that all those pieces are important, for sure. But it can all be undercut by a few for-loops that don't consider string re-allocations. That covers the "don't understand good code in the slightest, make big mistakes" side of things, but the other side is being able to think about the algorithm that is being run in your system (sometimes across multiple layers of code) and writing code that eeks out the highest performance from the system you're on in the programming language you're using. Also, to be clear, "the algorithm" here doesn't have to be super complicated or theoretical it can be as straightforward as assembling some data structure in response to a user's query across a few different sources. That process requires being able to write good code.