Upgrading to Xcode 13.2.1 seems to have fixed long launch times for our macOS app ! I had been waiting for a new update of BigSur to finally fix this issue. However, I have now updated to macOS 11.6.4, and Xcode 12.4 and the extremely slow startup our our large macOS app attached to the debugger was still 8 to 10 times slower than before upgrading to 11.3. Yesterday I decided to try Xcode 13.2.1. Our team has not officially switched to this compiler yet for but I can build and debug with a newer Xcode even though our CI computers are still using an older version of Xcode. I was initially a little disappointed because the full build time for the our very large macOS app was slightly slower than before upgrading to BugSur 11.3 and the older Xcode. However, I can forgive that as a minor inconvenience because now launch and begin debugging almost as fast as I was before upgrading to 11.3!