Your iPhone boasts a stunning ProMotion display, capable of silky-smooth 120 frames per second. Yet, browsing the web often feels…less fluid. The culprit? Safari, by default, caps its rendering speed at 60fps, leaving potential performance on the table.
Fortunately, you can unlock the full potential of your display with hidden developer settings called Feature Flags. These flags allow you to tweak Safari’s behavior, pushing it beyond its standard limitations. It’s a simple change that can dramatically improve your browsing experience.
On your Mac, begin by opening Safari and navigating to the Settings. You can access these using the Command + comma shortcut, or through the Safari menu in the menu bar. Within Settings, select the Advanced tab and click “Show features for web developers” at the very bottom.
A new tab labeled “Feature Flags” will appear. Scroll through the list, or use the search function, to locate “Prefer Page Rendering Updates near 60fps.” Simply deselect this option. A complete restart of Safari is then required for the change to take effect.
While most Feature Flags are intended for developers, experimenting with them is generally safe. However, it’s wise to document any changes you make. This allows you to easily revert settings if you encounter unexpected behavior. Some flags offer useful customizations, like disabling animations or lazy image loading.
The process is similar on your iPhone or iPad. Open the Settings app and tap “Apps” at the bottom of the screen. Scroll down and select “Safari.” Within Safari’s settings, scroll all the way to the bottom and tap “Advanced,” then “Feature Flags.”
Unlike the Mac version, there’s no search function on iOS. You’ll need to manually scroll through the alphabetical list to find “Prefer Page Rendering Updates near 60fps.” Toggle this option off. Again, a full restart of the Safari app is essential – swipe up from the bottom to access the app switcher and swipe up on Safari to close it, then relaunch.
As with the desktop version, proceed with caution when altering Feature Flags. Keep track of your modifications so you can easily undo them if needed. The benefit of unlocking higher frame rates is a smoother, more responsive browsing experience.
Be aware that allowing Safari to render at higher frame rates can impact battery life. The extent of the drain depends on your usage patterns and the content you view. Monitor your battery performance closely. If you notice a significant decrease, simply re-enable the “Prefer Page Rendering Updates near 60fps” flag and restart Safari.
