I could see the 100ms/7% impact coming into play for a super impulsive shopper going from page to page compulsively until they pull the trigger on a product. I wouldn't be surprised if that was a lot of Amazon's business—people buying things they had not set out to buy.
Makes less sense the smaller an e-shop gets since the consumer already needed intent to shop there. If I know I already want product X on Shop Y today, 10 second load times are rather inconsequential.
I've been thinking about that a lot lately. I have a medium-sized e-commerce. We sell hyper-customized products and, to be honest, the site's overall performance is not good. But when I looked into other stores in the same niche as ours, who are making a lot more money than us, I saw that their performance wasn't better than ours. I don't think people shop impulsively in our store because they have to customize the product and then make sure the customization is correct (it's a pretty complex customization). I believe that because the journey to checkout is so long and requires so much attention, the customers just don't give up due to high latency or slow responsiveness overall.
Makes less sense the smaller an e-shop gets since the consumer already needed intent to shop there. If I know I already want product X on Shop Y today, 10 second load times are rather inconsequential.