Tool · Reference doc, ~10 min to try

Throttling (Network and CPU) in Chrome DevTools

Chrome DevTools team, Google · Chrome for Developers Free Beginner

You cannot fix what you never feel, and most of us build on fast laptops and office wifi. This is the official doc for simulating Slow 3G and a low-tier mobile CPU right inside the browser you already have, so you can load your own site under the conditions your users actually face. Use it as a first cheap check before you ever get your hands on a real budget phone.

• Set the Network panel to Slow 3G to feel your real load time and spot pages that stall or ship too much on a patchy connection.
• Add CPU throttling (the calibrated low-tier mobile preset in recent Chrome) to catch janky scrolling and slow interactions a cheap Android chip would hit.
• This is a fast approximation, not the real thing: it is a starting point, and testing on an actual low-end device on a real network is still worth doing before you ship.