Believing those then 5-year old studies, we went in the opposite direction and intentionally slowed the site down in multi-variate testing. Out to 1000ms of intentional slowdown per dynamic page, we saw zero-point-zero change in ASV, CR%, and AOV.
We kept the faster experience, because "hey, why not?" and we'd paid all the NRE for it anyway, but the project was a technical success but a big bust versus business case.
Anything faster than 2-3 seconds has very diminishing if not 0 returns.
Before working hard to optimize speed, if you have a working site, try slowing it down and seeing if that makes a difference!
However, it's a quite easy test to run, so may be worth doing even if you can't stake your life on the results applying to a hypothetical speedup.
I am asking because I can imagine that people who are looking for a $5 item are more inclined to abort the search if it feels to slow while I assume someone looking to buy a $1000 item will persist.
Our analysis (for this project) was also limited to session and repeat session analysis, so we would have excluded any effects related to long-run increases in sessions from distinct shoppers (organic search traffic increase or cross-shopper recommendations). I believe those were small enough to properly ignore.
I'm definitely not arguing that page speed is bad, but do question the gospel that every 100ms is worth X% more traffic and conversions.
Instead when it came to revenue it was all implied (more people will stay on your site, they'll browse more pages, etc.) or an old statistic from someone else.
This is really just meant to be decent content, not a sales pitch. We obviously want to grow our business so we write about stuff that's close to what we do. Most people are really uninformed about site performance (still), you'd be shocked how many people don't even know about the 10 year old studies.
Also note, Amazon's -1% per 100ms of latency holds up for the ecommerce companies I've worked with. It's not a small number for any company, and we're actually really cheap for companies with a high value per user (like ecommerce! or saas!). You probably wouldn't serve billions of page views through fly with very cheap ads, though.
That said, I pretty much agree with you. We'll only succeed if we can keep proving that we're valuable. It's part of why we give enough traffic away for free that you can legitimately test us out. I don't particularly want people using us if they don't get any value out of it.