> Its a nightmare. It tends to be the kind of code you feel productive while writing ("I'm cleaning up this 200 line function"), but is really just making the codebase worse (is there a general term for this kind of false productivity? It's a common problem I see).

This issue is pervasive when Desktop/Web developers try to improve embedded software. I've achieved a thousandfold increase in performance by converting an embedded data logger from using printf to using a dedicated formatting function (most of the time was spent on parsing the format string and performing allocations).