Sorry, I can't add much, but the process on my machine (2Core 4T Intel Haswell, 16GB Ram, Samsung 860Evo SSD) took over 6 hours. Update was from 19.10 to 20.04.
$ grep "obsolete pkgs" /var/log/dist-upgrade/main.log 2020-04-30 20:17:50,550 DEBUG Start checking for obsolete pkgs 2020-05-01 02:39:51,833 DEBUG Finish checking for obsolete pkgs
Sorry, I can't add much, but the process on my machine (2Core 4T Intel Haswell, 16GB Ram, Samsung 860Evo SSD) took over 6 hours. Update was from 19.10 to 20.04.
$ grep "obsolete pkgs" /var/log/ dist-upgrade/ main.log
2020-04-30 20:17:50,550 DEBUG Start checking for obsolete pkgs
2020-05-01 02:39:51,833 DEBUG Finish checking for obsolete pkgs