Why Chrome?

[Moltke]

I always use Chromium (in preference to Firefox) on laptops 2, 3 & 4 (shown in footnote) for the simple reason that I've found it opens and runs/searches more quickly

Same here. In comparison with FF it's been my experience that it is a bit faster. I also use Opera from time to time and it is faster than FF too. On the technical part, I don't fully understand this but it's suppose to be a security threat https://dxr.mozilla.org/mozilla-central/...ral/search?q=specialpowers&redirect=false
Also https://medium.com/@neothefox/firefox-in...e2c8e08587

It has become apparent to us during an internal audit that Firefox browsers continued to send telemetry to Mozilla even when telemetry has been explicitly disabled under the "Privacy & Security" tab in the preference settings. The component in question is called Telemetry coverage

https://www.reddit.com/r/linux/comments/...s_to_send/

These might worth a reading too
https://www.ghacks.net/2018/09/21/mozill...opulation/
https://www.ghacks.net/2018/08/05/is-moz...dangerous/
https://www.ghacks.net/2018/03/20/firefo...eld-study/
https://www.ghacks.net/2018/07/28/mozill...x-updates/
https://www.ghacks.net/2017/10/06/mozill...ollecting/
https://www.ghacks.net/2017/12/16/firefo...hat-it-is/

Like I said, I don't fully understand all of that but then again many claim that is a security threat.