XCode 10 simulator slow

Is the common factor "slightly older MacBook Pro"? That's what I've got, and the simulators are totally unusable. They are, oddly, somewhat better if Slow Animations are turned on, though then of course the simulation is not so realistic and everything takes longer.

This is happening to me too.

I have up to date Mojave, XCode & Simulator. This is on MBP 2018. Everything is new and the simular is unusable.

My laptop sounds like its going to take off when I spin up the simulator. Before XCode 10 I never had an issue.

I've disabled dark mode and its still the same.

Even using the simulator stand-alone without XCode its unusable. I click on Safari and it often misinterprets the click and thinks I've held it for a long press.

I realize this is a late response, but I ran into this issue today and after searching on stackoverflow, I found that I had inadvertently pressed command+T, which triggers the "Slow Animations" (under the Debug menu in simulator). Pressing command+T again (or unselecting it in the menu) fixed the problem!

(I have option+command+T set to be a keyboard shortcut for the simulator's Hardware->Touch ID->Matching Touch command, I missed the option key and just hit the command+T accidentally, it didn't log in to my app, so pressed option+command+T again, then logged in and everything was sooooo.... slooooowwwwwww....... I thought some of the new code I added to the app caused a major problem, but removing it didn't help—it didn't dawn on me that I had hit command+T accidentally prior to this happening, then I found the stackoverflow answer, unchecked "Slow Animations" from the Debug menu, and all is back to normal!) Hope it's this simple fix for others who run into this issue.

Maybe you have put your debug in slowly animation.

Go to: Debug > Slow Animations

or

Try this ⌘T

The core issue here is that older versions of the simulator use the CPU for rendering. iOS 13 running on Catalina will utilize the GPU through Metal. You should have a much better experience with this year's releases.

Can you elaborate? I’m trying to decide what Mac to upgrade my 2011 MacBook Pro to and would like to make sure whatever I choose actually works. My MacBook is pretty much useless using the simulators.

I think the point is that you are not going upgrade your 2011 MacBook Pro. You are going to replace it.

I would like to share my knowledge with simulator performance issue. I have hybrid HTML5 + JavaScript app (web/android/iOS) and for android/iOS mobile apps I use web-view. I detected that some part of my app is extremely slow in Xcode simulator. It is part with Date object manipulations. When I run e.g. this simple JavaScript code

var x = new Date();
x.setMilliseconds(0);
x.setSeconds(0);
x.setMinutes(0);

in cycle with e.g. 1000 iterations it 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!). So simulator is 200 times slower! Terrible! Jsfiddle demo here: https://jsfiddle.net/kjms16cw/ I see in Xcode console error: "[IPC] Connection::waitForSyncReply: Timed-out while waiting for reply". Interesting is that Xcode during that 6 seconds show app CPU usage 0% but in host device (MacBook Pro) monitor I see that CPU increased from about 5% before to 50% during test. Dear Apple can you explain please that low simulator performance? So Im not possible to test my app in simulator at all... we also need simulator for testing but also for creating screenshots for several resolutions required before app publishing in app store. My app is for public transport and we need to do lot of date calculations each second (several hundreds) which usually takes 10 ms but in simulator several seconds and interval each second makes app totally unresponsive and unusable in simulator.

I had exactly the same problem and I decided to delete Xcode and all simulators that I had. After 5 years of continuous every (work) day Xcode usage it had a lot of garbage there. Then I installed Xcode again and things Simulator is now working properly.

Simulators are located under /Users/user/Library/Developer/CoreSimulator/Devices

Btw. when I was emptying Bin it had more than 1 million files to delete and I assume that was the problem why Simulator was so slow.