There's a huge difference between solving an instance of a problem and understanding the problem. Enough commits of "this seems to fix the problem" and the codebase becomes really hard to work with.
In this case, in my judgement, you only need to know about the delayed-ack/Nagling concepts if there's a engineering requirement to keep the flushHeaders call, and the 50ms latency is a dealbreaker (i.e. not merely a curiosity). Even then, it's not clear how to fix unless you can disable one of those features.