I see the matrix is more popular than xmpp, but why?
Agreed. The main advantage of something more efficient will be the ability to run instances on cheaper potato hardware.
I run a multi user environment with 4 fedi services, 2 other public websites, many surrounding services (ie heimdall, nginx, portainer, grafana, etc) and a minecraft server on one machine, I dont touch 10% cpu utilization. I get hundreds of hits per minute (which not a lot compared to big websites, i know).
I‘m probably gonna buy the cheapest banana pi or whatever equivalent and try running all of it on that machine just to prove that most people have no idea what they are talking about.
Hosting any fedi service today is no problem if you have skills and dedication. Any 4 core old laptop should easily do the trick, provided you immediately delete windows.
I run a system with an i5-4670.
My situation is much like yours, except I wrote a script which will suspend services when transcodes or game servers cause the system to approach resource capacity, to prevent more users from joining games and deteriorating the experience for everyone.
I know for a fact people using pies or old laptops can’t do what my system does, because I personally know people who have tried. They can’t even get a basic media server going that performs anywhere near mine, in the menus.