This is not the refresh rate of your screen.

Key findings:

• Safari throttles requestAnimationFrame to 50% of the screen refresh rate on both iOS and Safari when running in an iframe or in energy economy mode (iPhone, Macbook Apple Silicon). Firefox and Chrome don’t do this on macOS nor Android.
• Stability: Chrome is incredibly stable with a 0.01 hz precision 🤯 on both macOS and Android, while Safari and Firefox are okay-ish (maybe a 1 hz precision), but not as close to Chromium.
• External screen: on macOS (Macbook), Firefox seems to always follow-(ish) the refresh rate of the laptop screen, even when displayed on the secondary screen.
• Android: both Chrome and Firefox seem to follow the screen refresh rate in a rather stable way (but I guess it’s super hardware-dependant), and cut it in half when the app is not in the forefront.

Got other data? Please contact me and make sure to check the current page (it has no iframe), and this one (it has an iframe), with as much context as you can (browser version, device, OS, supposed screen refresh rate, what happens on energy mode, with the browser not focused…).

Come back soon: I’ll do some checks on Windows.