>Given that macOS automatically defragments sub-20MB files on the fly (which covers 99% of the files which affect perceived system performance) I'd wager money that your experience is 100% placebo.
Perhaps. I can certainly tell the difference performance when an overnight defrag run has finished, and I have no beef with you to prove or disprove a point.
If you're ever in North Cornwall, UK: drop me a line and I'll show you a before and after over a mug of coffee/tea/etc.
