I have the same problem in Xcode 13.3.1, macOS 12.3.1, iOS 15.4. Sometimes I wonder if Apple is serious about supporting SwiftUI. This seems like a really basic bug in an extremely common code pattern.

I've filed a feedback to Apple: https://feedbackassistant.apple.com/feedback/8701240

@devinthecold: No, for me the process taking 100-160% CPU is Xcode, for the entire time it's open, even when I'm not touching it. If I switch back to Beta 6, Xcode uses 0% when idle. I can switch back and forth between them and see the same behavior consistently. @KMT: 32 GB ram. 2.9 GHz 6-Core Intel Core i9. I have tried rebooting and the behavior didn't change.

I have the same problem with Xcode 12 beta 6 and an iPhone X running iOS 13.7. (It was working previously when I had 13.5 installed.)

I have the same problem with Xcode 12 beta 6 and an iPhone X running iOS 13.7. (It was working previously when I had 13.5 installed.)