It is definitely a good idea to check the system journal. If something
wrong is recorded there, there are likely many instances logged to cause
hours of unexpected delay.
I find it better to use ssh to connect to my RPi than to suffer its slow
graphics performance. Time information for a 'dnf upgrade" today on my
RPi (that included installation of the 4.14.14-300.fc27 kernel) appears
After the upgrade, a second run (with nothing to upgrade) takes 18 to 19
seconds of elapsed time.
I use a 32GB Samsung EVO memory card in my RPi. This data tells you what
I experience, to compare with your own system.
[root@rpi3-1 ryniker]# time dnf upgrade
Last metadata expiration check: 0:46:01 ago on Wed Jan 24 08:10:39 2018.
gdbm-devel armv7hl 1:1.13-6.fc27 updates 63 k
kernel armv7hl 4.14.8-300.fc27 @updates 0
kernel-core armv7hl 4.14.8-300.fc27 @updates 89 M
kernel-modules armv7hl 4.14.8-300.fc27 @updates 17 M
Install 4 Packages
Upgrade 85 Packages
Remove 3 Packages
Total download size: 189 M