Simulator on Xcode 10 became terribly slow

Question

Everything worked perfect on Xcode 9. But after updating to Xcode 10, Simulator started to get huge lags. Super simple animation is working on 2 fps and whole Mac OS is super sl

Answer 1

Yes, it is NOT about slow motion as you said. Xcode simulator has extremely low performance in global. It is Apple's bug. I have reported it via Feedback Assistant. I have created demo with code demonstrating that simulator is 200 times slower than any old real device. I have found that JavaScript code with Date object executed in WKWebView is pain for simulator. See jsfiddle https://jsfiddle.net/kjms16cw/ I hope Apple will fix it soon!

var log = document.getElementById("log");
document.getElementById("button").onclick = function() { run(); };

function run() {
	var d1 = new Date();
	for (var i = 0; i < 1000; i++) {
		var x = new Date();
		x.setMilliseconds(0);
		x.setSeconds(0);
		x.setMinutes(0);
	}
	var d2 = new Date();
	log.innerHTML = ((d2.getTime() - d1.getTime()) / 1000) + " seconds";
}

<h3>Xcode Simulator Extremely Low Performance</h3>
<p>This test runs fast (several tens milliseconds e.g. 30 ms)
in any browser any device any platform including very old iOS device
e.g. iPhone 5C and several years old iPad 2, BUT IN SIMULATOR IT TAKES 6000 ms 
(yes, 6 seconds!). Terrible!</p>
<button id="button">run()</button>
<div id="log"></div>

Answer 2

What worked for me was switching the values in Debug > Graphics Quality Override of the Simulator menu. Surprisingly, after setting to 'Low' from 'Device Default', lag was gone, and now any value works like a charm.

Answer 3

Make sure "Slow Animations" (Debug > Slow Animations) is not accidentally enabled. I've done it so many times :(

Answer 4

download iOS11.4 simulator and try it. The downside is you cannot test iOS12. But at least you can work on Xcode 10 and get the App released. Note: don’t bother to get Xcode 9.4.1. Or other versions. It won’t fix the problem. The trick is after you run Xcode 10 the first time, it installed the new coresimulator framework to your root folder.

Answer 5

I had same problem and this fixed it:

defaults write com.apple.CoreSimulator.IndigoFramebufferServices FramebufferRendererHint X  

Where X is:

0 = auto

1 = Metal

2 = OpenCL

3 = OpenGL

Answer 6

I had troubles when switching from landscape to portrait. views would just not move.

The only work around I found was Command + Arrow up. This simulates a volume up press, but also refreshes the display after the rotation