I've have set page load monitoring for employees and clients in grafana. Been asked to add device/locations dimensions. That's OK to know and understand how tech stack influences customer's journey. But that info has no impact on looking for a ways to optimize site even further. On slower device - site will be somewhat proportionally slower, but will remains times/percentage faster than any alternative being crafted without taking care about performance - related aspects. Key to understand that once you put your website under Cloudflare or any other CDN, it'll always be very close to where you live. I do not know for sure but I think I live 1.5km from data center where Cloudflare is hosting their server :) Of course here comes the rendering part. But if you have minimum JS, and sane images, and class-based CSS (they say it's fastest) - what is it what can slow you down? If delivery is fast because of cdn, rendering is fast because of sticking to basics and best practices, I think you have it all covered.