I'll have a go at explaining: The process described in the article isn't a simple recipe that you can apply to any program to achieve similar results.

`jq` is a command-line program that fires up to do one job, and then dies. For such a program, the only property we really want to optimise is execution speed. We don't care about memory leaks, or how much memory the process uses (within reason). `jq` could probably avoid freeing memory completely, and that would be fine. So using a super-stupid allocator is a big win for `jq`. You could probably write your own and make it run even faster.

But for a program with different runtime characteristics, the results might be radically different. A long-lived server program might need to avoid memory bloat more than it needs to run fast. Or it might need to ensure stability more than speed or size. Or maybe speed does matter, but it's throughput speed rather than latency. Each of those cases need to be measured differently, and may respond better to different optimisation strategies.

The comment that confused you is just trying to speak a word of caution about applying the article's recipe in a simplistic way. In the real world, optimisation can be quite an involved job.