[mickael]

I have written an article explaining the difference between Matrix and XMPP, and why it cannot be as scalable by design.

You can read it here: https://www.process-one.net/blog/matrix-and-xmpp-thoughts-on...

TL;DR: Matrix protocol is based on document replication and synchronisation, while XMPP is based on message passing. Matrix requires to constantly replicate and merge the data. It is an intended feature, but as it does more, you cannot expect to scale to the same level.

That said, we want ejabberd to be able to suit all types of messaging needs and we have already implemented 1-to-1 gateway with Matrix server inside the protocol. We are fine tuning our chatroom interop with Matrix. It means that we have already most of the code in place to support Matrix chat (as we need to implement the replication part). It means, the next step could be to implement full Matrix support for those who would rather use Matrix clients.

Disclosure: I am ProcessOne Founder, XMPP developer since 1999 and working on ejabberd since 2002.