Matomo 3.13.0 very slow loading and no tracking(?) after update to Php 7.2.10

Matomo was giving me warnings about using PHP 7.0, so I figured I should update and updated to php 7.2.1 via my ISP. However, after this update it Matomo is no longer working. All Matomo interface pages take a very long time to load (several minutes) and when they finish they just display the header and no visitor logs or traffic information. Interface panels for settings etc also take a very long time to load, but eventually do appear, but the panels with actual traffic information are all gone. The same for site pages with tracking, it seems that the matomo tracking code is not loading at all or maybe trying to run and eventually timing out.

I’ve tried using the System check and Activity log from the General settings screen, but these pages never seem to load. Anyone have any ideas for what could be causing this or how to get around the problem?

I tried downgrading to PHP 7.1.21 instead to see if that worked better. Using that Matomo is still extremely slow to load pages (compared to what it was previously on PHP 7.0) but now at least the traffic panels appear with “loading” statuses and indicators, and at least one time it eventually loaded the visitor log. I guess that’s better, but it still not working, and I’d rather use the later version of php 7.2.10 and get that working. Any ideas of what I can do to find out what’s wrong?

I finally got the Diagnostics page to load and there I see a warning about the server running on a NFS file system, which might cause it to be extremely slow on file-based sessions. I figure this might be the problem, but after finding how to configure this and setting “session_save_handler = dbtable” in config.ini.php I get no improvement, so I’m guessing this was not the problem. And it seems that the warning may be a little misleading? (System check – NFS filesystem warning)

Other than that, Still extremely slow, though I can now get visitor log data to load eventually on PHP 7.2.10, even though it’s more or less unusable as it takes so long for things to load and the diagnostics screen just time-outs with a 504 Gateway timeout error because it takes too long.