Mostly a reminder/clarification of things I knew, but a good and welcome one well-stated, because I probably sometimes forget. (I don't do performance work a lot).
But this:
> If you must use latency to measure efficiency, use mean (avg) latency. Yes, average latency
Not sure if I ever thought about it before, but after following the link[1] where OP talks more about it, they've convinced me. Definitely want mean latency at least in addition to median, not median alone.
There was an interesting article here not long ago that made the point that median is basically useless. If you load 5 resources on a page load, the odds of all of them being faster than the median (so it represents the user experience) is about 3%. You need a very high rank to get any useful information, probably with a number of 9s.
Can you say more about why you say the "real median" is hard to measure? It doesn't seem hard to measure to me, or any harder than a 99.99 percentile. Why is 50th percentile harder to measure than 99.99th?
But this:
> If you must use latency to measure efficiency, use mean (avg) latency. Yes, average latency
Not sure if I ever thought about it before, but after following the link[1] where OP talks more about it, they've convinced me. Definitely want mean latency at least in addition to median, not median alone.
[1]: https://brooker.co.za/blog/2017/12/28/mean.html