Many years ago I found myself looking at a performance issue with a new version of software. Re-written from the ground up and in a newer version of the language, it was running much slower than the component it replaced. It turned out the problem wasn't the code but the interaction between the client and server process. With only a single thread of execution (it was that long ago) a disproportionate amount of time was spent with the client requesting and the server providing 'progress updates'. The change from significantly slower to significantly faster performance was achieved with the alteration of a single line; the client process would request a 'progress update' once every five seconds, rather than 20 times every second.
Over a dozen years later and I'm at it again, only this time I'm the 'single thread of execution' and the numerous task reminders popping up on my screen are the work I'm keeping in the air whilst I carefully inch forward; either that or an elaborate April fool. I feel a circus act, not entirely sure why, but certain I must.