title: iOS simulator takes over 1 hour to run an app
body: <p>My Xcode and iOS simulator suddenly came to take too long time to run an app.
  The build itself can complete within 15 mins even if full-build, but after that, the Xcode's message box shows "Waiting for iPhone X to start" (of course, "iPhone X" is an example). Even after the boot of a simulator, the app installation is not started for a long time.</p>
  
  <p>Before the problem, the app installation was started once a build finished and a simulator booted.</p>
  
  <p>I doubted my code, so I also tried with another very simple code, but the same problem remains.</p>
  
  <p>Do you have any insights to help me?</p>
  
  <p>Xcode and iOS simulator: 10.1 / 
  Mac: MacBook 2017, CPU 1.4GHz i7, Memory 16GB, macOS Mojave 10.14.4</p>