Same here. Updated xcode & simulator yesterday and out of sudden ios apps when started show a white screen for seconds before the main application screen (i.e. a splashscreen) appears. Added print() to trace but it looks the delay happens not in user code. Looks like loading libs during the startup process takes ages before user code starts running.

Did some more testing. The white screen/delay only happens when the app is provisioned for debugging and started for the first time in the simulator. When i terminate the app and start it on the simulator again (w/o debugging from xcode) all went smooth. No white screen, no delay. So it looks like there is some kind of debugging/first run overhead that causes the delay aka white screen (system launch screen) to be visible for that long time.