Big Sur kill my machine: Mac (Retina 5K, 27-inch, Late 2015) 1TB Fusion Drive is very slow safari takes too much time and the startup time is a nightmare takes 3-4 minute Xcode lagging :(

Thanks for your quick reply 👋, I try to run your given code idea still nothing changes! Which version of Xcode ? My Xcode Version 13.2.1 (13C100) Did you inspect the disgnostics ? Yes! The window message says- TimeoutError: Timed out waiting for connection to DTServiceHub after 15.0 seconds. so I generate the report check attachment. previews_diagnostics_summary.txt simctl_diagnose_log.txt Please take a look. Regards!

The same problem happens to me after updating Xcode and building a project for iMac maybe. Apple devs working on it check this : discussion

Any updates?

Good News I have also tried a fresh OSX installation but the issue has not gone at all. Suddenly It fixed, maybe the last update from apple through a software update called "Command Line Tools for Xcode". Thanks to all of the Apple Devs and Frameworks Engineer who is tracking down the issue with me.