To get back on topic, France has really got its FOSS movement moving. There are a TON of Mastodon and Peertube instances located there. It's admirable.
By default, it sets up Synapse and a bunch of other services around it that are necessary to really make it useful (Postgres instead of the default under-preforming SQLite; mxisd as the identity server; STUN/TURN server for WebRTC calls; riot-web; various bridges; etc)
apt install matrix-synapse
and changing one yaml config to suit my needs
i am sure there is a dockerized version
I created 100 accounts for chatterbots. (This is not federated to the main Matrix network -- just local.)
The VM showed some lag when the chat bots connected and started inviting each other to their channels. But once all the invite sending/accepting settled down, it's been pretty smooth. It's randomized, but I think each channel has about 18 or 20 users.
The whole thing is using about 900 MB of RAM, and that's including everything -- CentOS, several containers, the Postgres database, Synapse, nginx, etc.
I run it on some 3usd vps i dont remember 1gb ram i think and use sqlite (its very portable this way). For about 20 people it works great.
It is not exactly efficient but overall still cheaper and better than other solutions ive found.
Footnote: IMO, the barrier for adoption for this kind of services has to be the lowest possible if it wants to gain any kind of traction. Mastodon and Peertube are good examples of this: docker-compose.yml in the project root, and in < 1 hour I got everything working by just setting a couple configuration values that were already in the environments section.
I figure that there is a lot of work going on right now so this might not be in the top priorities, but I really hope Matrix gets there soon.
Keep up the good work!