SOLUTION FOUND!

Here was the deal;

s9y config was configured to use the database server "localhost"

localhost on the box resolved to 127.0.0.1 -- and ALSO ipv6 ::1.

Recently, there was an ipv6 vulnerability on OpenBSD, and since we weren't using ipv6 on the host, the admin just block-dropped ...

Nothing on our server changed... but trying to get things back to normal, I changed

"Use persistent connections
Enable the usage of persistent database connections, read more here. This is normally not recommended"

from No to Yes.

and.... it works a lot better.

what the heck does that mean?

I ...

The other day, my s9y installation started loading ABHORRENTLY slow.

At first I thought it was an attack (someone might be pissed off at me) but then on closer look, other flat sites seem to work fine, even under the same domain name.

So i've checked the server -- requests are seen in tcpdump ...