Bug 294338 – Feature Request: Allow WKWebView to Support 120Hz Refresh Rate on ProMotion Devices

• Status: NEW
• Component: Layout and Rendering

[Fabian]

Following https://bugs.webkit.org/show_bug.cgi?id=173434, Safari now supports 120Hz via the "Prefer Page Rendering Updates Near 60fps" feature flag off on pro-motion devices.
Sadly, enabling this flag only affects Safari itself, but not hybrid apps using WKWebView under the hood.
It would be great to have an option to enable 120Hz support in apps using WKWebView, such that hybrid apps using canvas, requestAnimationFrame, and similar features effected by this, can use the full power of the device, since the difference between 60Hz and 120Hz is quite noticeable. As far as I am aware, there currently is no way to achieve this.

[Radar WebKit Bug Importer]

<rdar://problem/153131340>

[mdrejhon]

Thanks for reporting this.  I tried to override this for an app control (WKWebView, UIWebView) is hardcoded to 60fps last time I tested.

But...

It was still hard-capped to 60fps -- even if Info.plist setting for CADisableMinimumFrameDurationOnPhone is set.  

So yes it is a blocker for my ability to release a TestUFO app in the Apple App Store.

[Vaughan]

+1 for this, I have a painting app that uses webView, it would be great to have 120hz for smoother painting strokes, ideally without the user having to switch a feature flag.

[mdrejhon]

I'd even settle for a feature flag -- the feature flag doesn't even fix this problem at all.

As a native app, I can detect a 120Hz device running at only 60Hz, and automatically a dialog with an "Instructions" button (display step by step instructions).

There's a redesign of TestUFO underway that makes it more smartphone-friendly despite being originally designed as a desktop/tablet website, and a smartphone app launch would be perfect timing for my TestUFO layout retheming launch at end of year.

[Jeffrey Blanz]

If i’m not mistaken, this is the only reason Geforce Now does not offer 120fps support on iOS, iPadOS, and at least 90fps on the Vision Pro.

Also has the 60fps lock been confirmed on iOS 26?

I get 120fps when installing testufo as a Web App on iOS 26. I would think iOS automatically uses WKWebView for the web app. So maybe iOS 26 fixes this??

[Simon Fraser (smfr)]

> I get 120fps when installing testufo as a Web App on iOS 26

Did you change the "Prefer Page Rendering Updates Near 60fps" setting though?

I get 60fps in a Home Screen web app with default settings.

[Jeffrey Blanz]

> Did you change the "Prefer Page Rendering Updates Near 60fps" setting though?

Yes I changed “Prefer Page Rendering Updates Near 60fps" to Off and then I get 120fps in the web app. Which makes me wonder if with iOS 26 WKWebView does support 120fps if the feature flag is disabled?

Another note: If you install testufo as a web app on macOS 26, you will get 60fps even with the above feature flag disabled.

It’s possible forced web apps (websites that were not designed specifically to be a web app and the OS automatically wraps it as one) are installed differently on macOS and iOS and one uses WKWebView while the other does not.

[Fabian]

I think we should be careful not to mix different concepts here.

The original request was about "hybrid apps using WKWebView under the hood" (like capacitor by ionic) rather than web apps (talking about PWAs).
Even though there might be an issue concerning web apps too, I could understand the usage of the safari flag there, but not concerning separate apps downloaded on the App Store that use WKWebView. I think those apps should be able to stand alone.

[mdrejhon]

I dont know if macOS 26 fixes it but...

The MacOS before it has the problem of where you intentionally configure the Mac everywhere to turn off "Prefer Page Rendering Updates Near 60fps", you have webapp 120fps but WKWebView 60fps.

In other words, the same tweak doesn't apply equally to webapps and WKWebView.  In other words, webapps are defacto icons that launch a UI-less Safari browser (Apple executable) and WKWebView is a UI control compiled into your own application binary (your own executable with your own .plist file).