Most performance advice online assumes a baseline that doesn't exist for most of the world. Fast wifi, a recent phone, a stable connection. Lighthouse scores optimized for conditions half the planet doesn't have.
I build web products for businesses in Kenya. A meaningful share of my users are on 3G, sometimes 2G, often on a budget Android phone with limited storage and a browser that hasn't seen an update in a year. Here's what that actually changes about how you build.
Your bundle size is a business decision, not a dev preference
A 2MB JS bundle that loads instantly on your MacBook can take 15 to 20 seconds on a real 3G connection. That's not a slow load, that's a user who left before your app finished parsing. I've watched analytics confirm this directly, drop-off spikes exactly where bundle size peaks.
Skeleton screens matter more than animations
Every extra animated transition is more work for a weak CPU to render. I stripped most micro-interactions out of a recent build and page-perceived speed improved more than any code-splitting change I made that month. Motion is a luxury feature for people with headroom to spare.
Offline isn't an edge case, it's Tuesday
Connections drop mid-session constantly, not from bad code, just from the actual infrastructure. If your app throws away form state on a dropped connection, you're actively costing your users. Basic local persistence before submission became a non-negotiable for me after watching real users lose an entire booking form to a 4 second network blip.
Images are still the biggest offender in 2026
Everyone optimized images years ago and moved on. They didn't. I still regularly find production sites shipping unoptimized hero images at 3 to 4MB. On a fast connection that's invisible. On the connections a huge share of the world actually uses, that single image can be the whole page load.
The real point
"Fast" isn't a Lighthouse score. It's whether the app actually works for the person holding the phone it's meant for. A lot of what gets called premature optimization in tutorials is just basic respect for users outside wealthy, high bandwidth markets, which is most of the world's internet users, not a minority case.
What's the worst assumption you've seen baked into "best practice" web performance advice that falls apart the moment you leave ideal network conditions?
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