Re: System unusably slow after Debian upgrade.

[Dan Ritter <dsr@randomstring.org>]

G.W. Haywood wrote: 
> 
> As the box was still running Jessie I had to do the move in two bites.
> First move from Jessie to Stretch, then from Stretch to Buster.  The
> entire process was a bit long-winded and spread over a couple of days,
> but seemed to go smoothly enough.  Immediately, the users started to
> complain about performance.  Not just a small reduction, but the sort
> of thing that makes the whole system completely unusable.  My estimate
> after looking at the response on the desktop is several hundred times
> slower than normal for this box.  If you click on a message in the
> list of messages presented by the mail client, instead of seeing the
> message in under a second you can go and have a coffee break and still
> get back before it's shown on the screen.


 
> What can possibly cause such a drastic reduction in performance?

Go to /etc/nsswitch.conf

If these lines look like this

passwd:         compat systemd
group:          compat systemd
shadow:         compat systemd

remove the systemd references.

If performance improves immensely immediately after the edit,
that was the problem.

-dsr-