Ok so either I am going mad or someone is playing tricks behind the (Raspberry Pi OS) scene!
I slept on the problem overnight and came up with a few things to try. Interestingly, four rebuilds later (with SD, HDD and a few build sequence changes) Node-RED installed perfectly every time! There was no excessive CPU usage on any of the builds.
HOWEVER in each build syslog was missing. Searching showed the file did not exist. Indeed /var/log/ contained very few files at all compared with similar builds. e.g. no kern.log, messages, auth.log, etc. I do not know what all of these file are for but seems to me that they ought to be there.
What I have discovered is that the image downloaded via Raspberry Pi Imager has changed from bullseye to bookworm between 9/10/23 (High CPU Usage) and today (Normal CPU Usage). Hmm.
There are differences in the nodered-install.log's generated between those dates showing this change of OS including the appearance of the line...
W: http://raspbian.raspberrypi.com/raspbian/dists/bookworm/InRelease: Key is stored in legacy trusted.gpg keyring (/etc/apt/trusted.gpg), see the DEPRECATION section in apt-key(8) for details.
I've no idea whether this is significant or not!
In (my) conclusion the change of OS fixed the Node-RED issue but introduced the total lack of system logging.
O Joy!
