Some of the stuff I’m personally most excited about right now is Hydrogen (https://github.com/vector-im/hydrogen-web): a super lightweight web client which heavily leans on indexeddb for storage and so minimises RAM. My primary account has 3000 rooms and about 450K visible users - on element-web this uses 1.1GB of RAM, but on hydrogen it uses 14MB :) We’re also looking at glueing E2EE into Hydrogen via the crypto layer of matrix-rust-sdk, which could be a massive win in terms of reusing and auditing a robust safe implementation for the Hard problem of encryption, rather than implementing it from scratch every time in every new client.
Dendrite (go server impl) progress is also very promising - we’ve been focusing on it (at last!) since the beginning of the year, and going to enter beta in the next few weeks. A typical small/medium live server is currently using 57MB of RAM (rather than synapse’s ~500MB). We haven’t started optimising yet :)
Synapse has also finally come of age - the whole codebase has almost been switched to twisted/asyncio rather than twisted deferreds, which both speeds things up a bit but also gives us way better visibility on profiling for future perf work. Almost all bits now scale horizontally (apart from the master dispatcher process). Synapse isn’t going away - we see Synapse and Dendrite coexisting much as Apache and nginx coexist today.
Conduit is also super exciting as an entirely community developed Rust homeserver, which currently runs ~10x faster than either Synapse or Dendrite (but doesn’t federate yet, or scale horizontally). It’s really fun to see an indie FOSS server implementation properly take off :)
Finally, P2P Matrix is coming together well - compiling Dendrite to WASM and running it clientside, using Yggdrasil currently as an overlay network to tunnel through to other P2P nodes.
In short: the Matrix ecosystem is in a fairly healthy place right now - the next gen of clients and servers should be incredible :)