This issue seems to be fixed in macOS 26.3.

@DTS Engineer For my loadHTMLString issue I did report via Feedback Assistant with a minimal test case to reproduce the problem (case: FB21630407). @jfahrenkrug I haven't found a solution or a workaround. It's oddly an issue only on macOS 26.2, not on iOS/iPadOS 26.2 or 26.2.1.

I am also able to reproduce a consistent ~3s delay on macOS 26.2 for iOS apps running on Mac that use Swift + WKWebView. The delay is before page navigation even starts. Measured timings (ms): WKWebView init: ~47 Delay between loadHTMLString and didStart: ~3000 Render finish after start: ~23 On iOS 26.2, the delay between loading HTML and starting is only 20ms. Sharing WKProcessPool and pre‑warming a WKWebView (kept alive) did not reduce the ~3s delay. This looks like a WebKit process startup regression specific to iOS/Designed for iPad apps using Swift + WKWebView running on macOS 26.2.