Re: System unusably slow after Debian upgrade.
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.