You can also fix this by setting a wallpaper in the Simulator. The iOS 26.1 simulators are missing the default wallpapers, which can trigger a crash or loop in the MercuryPosterExtension. This has happened several times in the past with other Xcode releases. I’m not sure how to set a wallpaper in the #Preview Simulator, but with this workaround you can at least debug and run apps in the regular Simulator without the high CPU load.