After the second boot, I opened a console and did a 'dnf update'. With a fast ethernet connection, it has taken nearly 12 hours to complete. It is currently in the 'top' shows nothing CPU usage to be 2.3% for the top process and nothing much for anthing else. The dnf process occasionally pops up in the top list, using less than 1% of the cpu, though about 18% of memory.
Is there a zombie thread running somewhere ?
I'll investigate further once the update process is complete.