I've experienced this since installing Xcode 12. It makes debugging on a device really painful. Interestingly it does not seem to be a problem with an iPhone 6s running iOS 14 but is a GIGANTIC problem with my iPad Pro and iPhone 11 running iOS 14. I have found a marginally useful workaround however. If I change the Run scheme to "Wait for the executable to be launched" instead of "Automatic" the problem goes from being absolutely insufferable to only somewhat annoying. It still takes a bit of time to go from the launch screen to the main screen but nowhere near as long as when in "Automatic" mode. So change the project's run scheme and hit "Run", the code will compile and install. Launch the executable manually, then breathe calmly for a minute or so and everything should be working. Well, it does for me. Good luck. Hope this helps some of you - Apple really needs to fix this. You just can't debug everything on the simulators!