XCode 10 simulator slow

We have several mid-2011 27" iMac (3.4 GHz Intel Core i7) running High Sierra 10.13.6 with Xcode 10. All exhibit the same slow-down when trying to use the Simulator. If the Simulator is left running in the background the entire OS will eventually come to a halt until the Simulator is forcibly stopped.

Seems to be slightly less of a problem on some newer Macs (e.g. mid-2017 MacBook Pro; mid-2013 27" iMac).

Either way, it's making development for our team extemely difficult.

Will try running ‘xcrun simctl diagnose’ and ‘sudo sysdiagnose -q’ when in this slowed state and attach the resulting tarballs to a bug report to see if that helps with any form of recognition / diagnosis.

FYI - this workaround might help some of you in the meantime, but we've noticed that if you run the iPhone 5S / SE - 7, the slow-down is not as prevalent. Any newer devices are more or less unusable from the moment they open.

Start up times of my apps:

iOS 10: 2 seconds

iOS 11: 3 seconds !

iOS 12: 4 seconds !!

Also slow on iOS 12 device. SetImage: extremely slows down. When commenting them startup is fast.

buttonPhoto setImage:[UIImage imageNamed:@"photoNormal7.png"]   forState:UIControlStateNormal];

As a trial I removed assigning of images to UIButton from start-up and processed it after start-up separately, also on main-thread. Total 47 setImage: or setBackgroundImage: take 1 (iPhone SE) or even 2 seconds (iPhone 8 Plus) on iOS 12 simulator !!

  buttonPhoto.contentMode = UIViewContentModeCenter;
  [buttonPhoto setImage:[UIImage imageNamed:@"photoNormal7.png"]   forState:UIControlStateNormal];
  [buttonPhoto setImage:[UIImage imageNamed:@"photoDisabled7.png"] forState:UIControlStateDisabled];
  [buttonPhoto setImage:[UIImage imageNamed:@"photoDisabled7.png"] forState:UIControlStateDisabled|UIControlStateSelected];
  [buttonPhoto setImage:[UIImage imageNamed:@"photoSelected7.png"] forState:UIControlStateSelected];
  [buttonPhoto setImage:[UIImage imageNamed:@"photoHighlighted7.png"] forState:UIControlStateHighlighted];
  [buttonPhoto setImage:[UIImage imageNamed:@"photoHighlighted7.png"] forState:UIControlStateSelected|UIControlStateHighlighted];

Setting of contentMode to center, so it shouldn't scale, didn't improve performance. The images exist as 1x, 2x, 3x (eg. photoNormal7.png, photoNormal7@2x.png, photoNormal7@3x.png).

SOLUTION: Usage of image asset catalog (xcassets).

Xcode 10 / 10.1 beta, macOS 10.14, MacBook Pro 13" 2018, 2.7GHz 4-Core, 16 GB

Yeah this is crazy and needs sorting ASAP!

Is there an active bug / issue somewhere that i can +1?

Having the same exact issue.

The iOS 12 simulator is practically unsable.

Make sure you don't have slow animation turned on, Command + T or the debug menu.

Is there any official word from Apple about this or are they just attempting to get developers to fork out for the actual devices and or newer more powerfull and expensive devices to work from as with so many threads on this issue over so many different versions and years without it being addressed it sort of feels and looks like its intentional.

Thank You Alexandra, I think your comments have put me on the path to correction.

Mojave ? huh? I believe that this and the dark mode is what is causing most of these SimulatorApp problems.

After reinstalling way too many versions of iOS, I've found 9.3 most reliable for tableView scrolling etc.

My Catch-22 is that ":-1: WKWebView before iOS 11.0 (NSCoding support was broken in previous versions) [6]"

Transition from 10.13.6 to 10.14.1 is going to put thousands of developer - users offside.

The unusable view problems - scrolling - would seem to be a function of GPUs and more specifically Metal compatible GPUs.

I understand the true black of oLED, vLED etc is attained by turning off a layer of molecules, ie. On 0x000000 or OFF (no electrons).

Don't know whether this switching saves power, but makes sense why you might transition all your mobile devices to oLED.

I call Apple's Dark Mode the darkside. Surely they wouldn't have done this purely for the gamers love of the dark aesthetic. Would they?

Anyhow I don't like it. Might be able to dust off that old VT52 VDU with monochrome green display sitting at the back of garden shed.

My perfectly functional iMac with partitioned SSD, circa 2012, does not fit the bill. If I read the release notes right, bootcamp also goes.

Mojave compatibility details here.

Hope this helps others.

nb: By actually turning pixels off also improves contrast and readabilty of wearable devices when outside.

Yeps, there's a scrolling insets (include inertia) lag / frozen problem since Xcode 9 (10 too) but only occurs on iPhone X/XS/XS Max Simulator.

When using macos 10.13.6 and xcode 10 on mac pro 5.1, starting the simulator it's getting so slow and lagging, that you cannot work. Also entire system is getting slow. Rolling back to xcode 9 woun't help. Only time machine helps. Rolled back to 10.13.4 and xcode 9. Tried xcode 10.1 beta, the problem still exists. Can't update this mac to Mohave because of Apple requires only cards with metall support((

I had the same problem with very slow simulator behavior on my Mac Pro 5.1 with XCode 10 (12 cores, 128GB RAM); simulator performance is fine on my Macbook Pro using XCode 10

In order to upgrade to Mojave I swapped to a metal-capabile GPU (supplied a few years ago by a well-known ******* based in Hollywood) and that solved the problem (well, either the graphics card or the Mojave upgrade did)

Same issue here with Xcode 10, High Sierra 10.13.6, Macbook Pro i7 with SSD

The simulator is unusable.

This has helped me in getting more performance improvements out of Xcode 10 but I just want to forewarn you all that I'm running macOS Mojave 10.14.1 beta 5 and Xcode 10.1 beta 3.

If those technical specs are not applicable to you, kindly disregard the following next steps I'll be presenting to squeeze more speed, optimal performance and efficiency out of your iOS Simulators running iOS 12 and above.

The reason why I specify these specs is because I've been downloading every single beta release since Mojave first came out and have been closely following each sequential release as a means of tracking which bugs have been addressed or fixed and if any beta release actually provides more optimal performance to my machine.

In this case, since we're discussing Xcode 10, let's begin:

• First order of business: get rid of Dark Mode altogether, you don't need it as much as you think you do. It's gimmicky and actually slows down your performance on Xcode in every shape and form. Notice that weird lag when you're trying to get your iOS Simulator going while simultaneouly browsing Chrome? That has definitely been attributed to Dark Mode in my case and I have seen a substancial difference in performance when running my apps on the Simulator.
• Turn off your device bezels by doing the following: Simulator > Window > Show Device Bezels (uncheck it if it checked by default).
• If you haven't already, be sure that you're slowing your animations: Simulator > Debug > Slow Animations
• Also, we're going to minize the quality of our graphics by doing the following: Simulator > Debug > Graphics Quality Override > Low Quality (although Device Default works just as well, quite frankly. There is no literal difference graphically between Low Quality and Device Default. They both present themselves quite similarly).

Since applying the following changes to my Simulator preferences, indexing takes less effort out of Xcode, launching the Simulator itself is almost instananeous and app installation happens in seconds. While it's not the record speed that I'm used to from Xcode 7.3.1 or even Xcode 9.2, it makes version Xcode 10 a lot more usable than before I implemented some changes on machine settings.

Again, I haven't tested any of these changes on Xcode 10 GM so this could potentially help just about anyone even if they're not running macOS Mojave beta or even Xcode 10 beta versions. I simply wanted to emphasize that my machine could be different than yours in the aspect that I'm running beta software so implement these relatively harmless changes at your own discretion.

Although Xcode 10 is installable from High Sierra, it is not optimally compatible with that macOS version. Try macOS Mojave instead.

I have the same issue... and I've been having it since Xcode 9 actually... I quickly decided to try the 10 beta hoping it was fixed.

But nope - I have all the latest updates to Mojave and Xcode and the Simulator most of the time is unusanle. It takes multiple clicks (like 10-20) to perform an action like touch, and then it takes a few seconds to do the action. I don't know how to fix it 😟 - reminds me of Windows.

This is on a 2017 13" MBP