Build / Run Xcode takes more and more time


I’m very unthusiastic about the courses but since 4 days my MacBook and related Xcode is extremely slow.
Typically to build and run the CollectionView exercise at lesson 3 it takes more then 15 minutes.
Does anyone has an idea what to do. On the internet is see many topics on this subject but no real solution.
I have Mac OS High Sierra en XCode 9.2 (9C40b)
It is annoying because all the fun of making the exercises / challenges is now gone.

A happy new year to all,

Hi @luclannoo,
One of the issues with the new builds of Xcode after 7.0 have had veteran developers complain about them too. There are too many things that are happening including source code coloring, to compiling for pre-compilation errors, syntax checking, etc. Source Kit can be a major contributor to this lag/delay. You can start Activity Monitor to check for what is slowing your machine down.

Swift is fun and it is a bit of a let down that the crispness of Xcode is down compared to earlier versions. However, do not let that deter you, you could kill SourceKit (if that is the main culprit) and you can literally gain your system back.

Hope to hear the fun you had learning Swift,




Jayant, this is my biggest problem. In the activity monitor I see that PC is doing almost nothing. (95% inactive).
The only process that is running and taking time is CoreSimulatorService.
I expect this is normal when building the app for usage on the PC with simulator.



Hmmm, that is strange, CoreSimulatorService is the simulator, and that should not interfere with the build process.
What kind of RAM do you have on your Mac and do you have enough disk space? What version of Xcode are you using?

If I come across other factors that could cause this issue, I’ll update the response here.



Here my system parameters.

MacBook Pro : macOS 10.13.2
Memory : 8 Gb
Disk : SSD 167Gb available from 250
XCode 9.2 Build 9C40b

I’m thinking to re-install my full Mac but i’m afraid this will not help.
Could this be a HW problem. Sometimes my Mac just crashes without any sign / reason.

Thanks for your replies,


Hi luclannoo,

I have a similar Macbook Pro:

MacBook Pro : macOS 10.13.2
Processor: 2.7 GHz Intel Core i5
Memory : 8 Gb
Disk : SSD 78Gb available from 250
XCode 9.2 Build 9C40b

and, so far, my builds take less than 30 seconds with Xcode 9.2.

If you post your app somewhere (Dropbox, github, etc.), I’ll run it on my Macbook Pro and report back how long the app takes to build.

Sometimes my Mac just crashes without any sign / reason.

I don’t think that has happened to me. My Macbook Pro is an early 2015 model.

I can send you the code but it is the same code as in the tutorial (CollectionView after video n° 4).
So it should take only some seconds.

On my PC it takes easily more then 15 minutes. So the request for help is to find a way to detect where the problem is.
I already reinstalled MacOS en XCode.

So i’m stuck.


Suit yourself…

The general consensus seems to be that Xcode 9.2 is a turkey. Check the “glowing” reviews on the App Store. I am sticking with 9.1 for the time being.

@7stud and @davejewell

To both, thanks for feed-back.
After reinstalling Mac Os and Xcode even a fully empty project compiles and runs in more then 15 minutes and lock fully my PC.
I have decided to bring them to an Apple repair center.
I think there is a Hardware problem too.


PC back from repair.
Malware deleted.
Antivirus was hanging up PC.

Xcode now again to acceptable speed.
I can continue my learning.

Thanks to all !

Hi @luclannoo,
Never thought that the Anti-virus was causing the delays…
Been working on Macs far too long, had forgotten how it was on Windows with all additional stuff clogging up the system.

Glad that you got your mac and xcode working and all good in terms of speed.



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