puzzled by browser differences

I upgraded from Zen FTTC 80/20 to their Fibre 900 service at the beginning of the year. Obviously I wanted to check the speed, and I used my usual selection of 5 assorted web sites, with my normal Firefox browser.

My average speeds over a month were 915/665. Nothing to complain about, I thought. However I then tried the same tests using the Chrome browser and I measured 924/905.

As far as I know there are no special circumstances with either browser, so I'd be grateful for any suggestions. I'm not bothered by the 30% reduction in upload speed, just interested in what may be causing it.

Zen have IPv6, Chrome no longer honours the original RFC for dual stacked systems, it has a happy eyeballs mechanism where it connects to both stacks and uses the one that responds first.

So assuming default windows prefix configuration, Firefox on a dual stacked system will always use IPv6 when available, whilst Chrome will use the stack that responds first.

There may be other differences as well affecting it, as they are different browsing engines.

IPvFoo extension would confirm if its stack difference.

Edited by Chrysalis (Fri 24-Feb-23 00:53:29)

Well, thank you for your response, but I'm sorry to say that I didn't understand a word of it.

You did ask on a technical forum.

The basics of IP4 v IP6 are easy enough to read up aboutt.

As well as the different page rendering engines already mentioned, and different levels of hardware acceleration (what tasks can use the GPU) there may be different add-ons or extensions involved.

With Firefox there is a profile manager that amongst other things would let you create a new profile with the default settings for that version.
You may also be able to temporarily disable any add-ons.

about:profiles will show if you have more than one profile already created.

Other things that can influence reported speeds include any internet security software, as it may hook into browser, email and other online applications in different ways.