Quack,
Sandro noticed some posts did not appear quickly on the interface.
There's quite a lot of traffic and it was not keeping up, so I added a
vCPU (2->3), but I had to restart the VM but it was fast.
I also noticed some MM crontab maintenance jobs did trigger an OOM
killer, so I added a bit more RAM (4GB->5GB).
Another thing to consider is: we also filter outgoing mails, which is
nice to avoid being blacklisted if some bad guy subscribe and post
spammy content. But it seems postfix is applying a recipient concurrency
of one when sending to the filter, which means if the list has x
subscribers then it is checked x times, which is silly. There is no such
thing in the configuration so I'm looking into it. This probably affects
other installations but this one being heavily loaded…
\_o<