iphone simulator suddenly started running very slo

问题:

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 loading content and animations. I have not made any changes to my code since I last tested it successfully.

I tried restarting the simulator (multiple times) and removing the app and doing a completely clean rebuild, but no luck. I also checked my cpu usage through the monitor while the simulator is running and I am only using about 30% of my cpu and 40% of memory.

I fully understand that the simulator is never a quick as the device itself, but it seems strange that it has suddenly started running slow after such a long time, and by slow I mean less then a quater of its original speed.

回答1:

In the iOS simulator, at the bar on the top, click on Debug -> Toggle Slow Animations. Chances are you accidentally toggled it on.

回答2:

Simple Command + T will fix this problem.

Command + T toggles the simulator's Slow Animations, which can be found under the Simulator Menu: Debug -> Slow Animations.

回答3:

Go to the simulator's Debug menu and select "Toggle Slow Animations".

Update: In Xcode 10, it's just "Slow Animations":

回答4:

Select Simulator,

Select Debug and uncheck slow animation.
shortcut command + t

That's work for me.

回答5:

If the Cmd-T (slow animations) option doesn't work for you and Debug -> Slow Animations is off but you still have slow animations try Simulator -> Reset Contents and Settings (or possibly Hardware -> Erase All Content and Settings). That worked for me when none of the other answers in here did. Anyone have a suggestion as to why?

Also having a debugger attached (at all) may make the animations very slow.

回答6:

Another potential fix for React-Native users:

Chrome de-prioritizes Javascript running in any tabs not in the foreground. So if you have enabled remote debugging, be sure to put the debugger in its own window.

回答7:

You accidentally pressed the slow animation on debug when using simulator. So Run Simulator -> Debug -> Uncheck Slow Animation.

回答8:

I think you pressed command + T instead of command + R by mistake.

回答9:

I don't have the rep yet to leave a comment, but I upvoted some answers here and wanted to say more. I had a problem with slow animations in the iOS Simulator, especially on rotation, and I found this post via Google. Indeed, somehow "Toggle Slow Animations" must have been on, because three shifts fixed it. At first, I didn't think this was a problem because there's no checkmark next to "Toggle Slow Animations." It turns out there's never a checkmark, or any indication from the menu whether it's on or off. So just try toggling it and see if the rotation/navigation is faster/slower.

So, thank you!

回答10:

Simulator -> Reset contents and settings works for me. The issue seems to reappear when I debug my react-native code remotely. It could also be to do with AsyncStorage as nomad suggested.

回答11:

You can try to turn off remote debugging (Cmd-D -> Stop Remote JS Debugging). That usually speed things up.

回答12:

When the chrome debug is active and the browser tab is not in the foreground, the emulator is slow too. For me, I decided to put the guide in the foreground.