I can't contradict your claim (since I don't work on mass-market sites), but I test my work on a VM with 1 CPU and 1GB ram; if the site doesn't run well in that, it's not good enough. I wish more people tested their software that way. I often find myself performing optimizations that are generally best-practices under V8 (and also work well in Firefox) that most in this community would consider "premature optimizations," at least until you point out that the difference between the two are 20-50x, and something that once cost 40ms now costs under 1ms, meaning your UI is just that much more responsive. For some reason, "it works, I'm done" seems to be a pervasive mental model. How unfortunate.