edit: also https://github.com/Cadair/skill-matrixslack
edit: also https://github.com/Cadair/skill-matrixslack
There is a replacement homeserver (https://github.com/matrix-org/dendrite) but it's not done yet.
Also, client support is awful. The only one I can reasonably tell a non-technical user to use is Riot - but that's somehow more resource hungry than the Slack desktop app. There are good ones, but they are either only for technical users (weechat) or are extremely barebones (nheko, quaternion).
We're basically doing nothing but fixing Synapse's performance problems currently, and improvements are on the horizon. We're late because we got sidetracked fixing flaws in the protocol, but as of the last few weeks we're back on perf again. So far we've sped up /sync by 2x and reduced CPU by about 20%, but the RAM improvements should land over the coming weeks unless we have further distractions.
Meanwhile, on Riot, we're busy landing performance fixes which should make it much less resource hungry than Slack. These are literally landing as we speak: https://github.com/matrix-org/synapse/pull/2970, https://github.com/matrix-org/synapse/pull/3331 etc.
I mean, my 10-active-users off-the-shelf XMPP server (ejabberd) uses about 100MB RAM currently.
Fit for orgs with external partners, providers, customers, freelances, remote and home office workers...
edit: btw, the number of comments you've made in this thread to “sell” your solution is… abusive?
It's actually not as bad as I remember (time made me think it's worse than it really is) - it's really only large rooms that feel slow. Oops.
I just guess the whole thing doesn't feel responsive. Messages sent take a while to sync between different clients, etc.