Speaking as the project lead for Matrix; we are continuing to work on Synapse's RAM use, and it will only get better over time.
One big misconception is that somehow RAM usage is related to the number of users on your server - instead, it's related to the size & complexity of the rooms your users are participating in. In other words, one person who joins thousands of rooms with thousands of users in them will use a lot more RAM than a server with a thousand users who use it only for small group chats.
The things to check if your Synapse RAM is high are:
* Make sure you're running postgres. Sqlite is not currently
usable in production.
* Make sure you're running Python 3.7
* Increase the synapse cache factor a bit.
* Check for and prune extremities (https://github.com/matrix-org/synapse/issues/1760), which will soon be a thing of the past, but we're not there quite yet.
If it's still overloaded, then you need to look at splitting the synapse master process off into workers (https://github.com/matrix-org/synapse/blob/master/docs/worke...) or disabling presence.
In terms of whether you get response in the support rooms - whilst the core team has been preoccupied with infrastructure security over the last few weeks, the rest of the community is generally happy to help with synapse tuning and the rooms are far from idle...