iPhone Simulator suddenly started running very slow

Question

I have been working on an app in iphone simulator for a number of weeks and it has been running well up until now, but all of a sudden has begun running very slow both when

Answer 1

In the iOS simulator, at the bar on the top, click on Debug → Toggle Slow Animations (or Slow Animations with Xcode 10+). Chances are you accidentally toggled it on.