Thanks.
Yes, the reference to Bitdefender VPN is a leftover from a previous installation (despite running the deep-clean Bitdefender Uninstall Tool). Should I just delete this file?
I ran the patcher. Calibre, Etcher, Core Temp utility and VLC Media Player were updated.
I have significantly reduced the number of FF extensions, although not below 8.
Since we begun this exercise the PC seems to be running a lot smoother. The internet connection feels quicker. I'll continue to monitor over the next few days and report back with any problems.
Thankyou very much for your assistance.