I'm not sure if it is the same phenomenon but I was really disappointed with the performance of a python aiohttp server [1] when I went from the application serving an html page with maybe 2-3 small images that would stick in the cache (icons) and instead was serving 20-50 photographic images per page, particularly over the wrong direction of an ADSL connection.

I thought this was low CPU but it was not low CPU enough, in the end I switched to gunicorn (running in WSL) with IIS fronting and serving the images (woulda been nginix in a pure-Linux environment) I think the tiny amount of CPU to serve the images was still getting blocked by requests that used a little more CPU. With gunicorn I'm not afraid to add tasks that crunch on the CPU a little harder too.

[1] built a lot of mini-apps that worked great before