How to Enable Full 120Hz ProMotion Scrolling in Safari
If you’ve invested in a ProMotion-capable Apple device, you expect consistent high-refresh-rate output across the board. Yet, Safari often feels sluggish compared to the snap of the home screen or the fluidity of third-party browsers like Chrome. This isn't a glitch—Apple intentionally caps Safari’s rendering at 60Hz. While the official line is "energy efficiency," the reality often comes down to aggressive thermal management; keeping the GPU from ramping up prevents the device from getting warm during long browsing sessions.
Fortunately, Safari 26 (released in late 2025 with iOS 26 and macOS 26) retains the experimental toggles needed to bypass this restriction. By adjusting a specific feature flag, you can force Safari to match the 120Hz capabilities of your hardware.
Hardware and Software Requirements
Enabling 120Hz Rendering on iPhone and iPad
Apple buries its most impactful performance tweaks within the system settings to prevent the average user from inadvertently tanking their battery life. For those seeking maximum responsiveness, the path is hidden under the Advanced menu.
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Open Safari Settings: Go to Settings > Apps > Safari.
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Enter the Lab: Scroll to the bottom, tap Advanced, and then select Feature Flags.
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Kill the 60fps Cap: This list is extensive. Use the search bar at the top to find a flag titled prefer Page Rendering Updates near 60fps.
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Toggle it OFF: By disabling this flag, you remove the instruction that tells Safari to prioritize a lower frame rate.
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Hard Restart Safari: The change won't take effect until the process is killed. Swipe up to the App Switcher, toss Safari away, and relaunch it.
To confirm the change, head over to a site like TestUFO. If the flag is successfully disabled, your frame counter should finally hit the 120fps mark during active scrolling.
Activating 120Hz Rendering on macOS
On the Mac, the process is slightly more involved because you first have to expose the developer tools that Apple hides by default.
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Unlock Developer Tools: Launch Safari, go to the Safari menu in the top bar, and select Settings. Navigate to the Advanced tab and check the box at the bottom for Show features for web developers.
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Access Feature Flags: You’ll see a new Develop menu in your Mac's top bar. Click it and select Feature Flags.
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Filter and Adjust: Type "60" into the search field. Uncheck the box for prefer Page Rendering Updates near 60fps.
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Relaunch: Completely quit Safari (Command + Q) and restart it to initialize the new rendering parameters.