Bug 298226

Summary: [iOS 18.6 Regression] Page load takes ~24s in Safari/WebView due to WebKit rendering/JS execution slowdown
Product: WebKit Reporter: Deepak <deepak.srivastava>
Component: New BugsAssignee: Nobody <webkit-unassigned>
Status: RESOLVED DUPLICATE    
Severity: Critical    
Priority: P1    
Version: WebKit Nightly Build   
Hardware: iPhone / iPad   
OS: Other   

Deepak
Reported 2025-09-02 06:22:43 PDT
Product: WebKit (Safari / iOS) Version: iOS 18.6 (WebKit 618.x – Hardware: iPhone 14 / iOS 18.6 (also reproducible on other iPhones) Steps to Reproduce Open Safari on iOS 18.6 (or any WKWebView in an app). Navigate to [https://www. dentsplysirona.com/de-de] Observe load time and rendering. Expected Results Page loads in ~2–3 seconds (normal load time on iOS 18.5 and earlier). Layout renders progressively, no long blocking tasks. Actual Results Page takes ~24 seconds to fully load. Rendering stalls before first paint. Same page on iOS 18.5 loads quickly, so this appears to be a regression introduced in 18.6. Additional Notes- Issue affects both Safari and in-app WebViews (WKWebView). Desktop Safari 18 (macOS) does not show this issue. Clearing cache/cookies does not help. Happens consistently across multiple sites with moderate JavaScript and CSS payloads. Possibly related to JS parsing/render pipeline regression introduced in iOS 18.6.
Attachments
Alexey Proskuryakov
Comment 1 2025-09-02 08:37:56 PDT
*** This bug has been marked as a duplicate of bug 298222 ***
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