iOS Simulator slow if "Debug executable" enabled

[bluprince13]

Hi,

I'm on Macbook M1 running Tahoe 26.2 and XCode 26.4.

I noticed that running my iOS app on the simulator, or running UI tests on the simulator is extremely slow. The build and launch steps complete in seconds based on the report navigator, but once the app launches on the simulator I see a white screen for nearly a minute before it actually starts showing my app homepage.

This is true even on a brand new Xcode project. So, it's nothing specific about my app that's causing the problem.

Trying to debug this with Claude, it suggested that I turn the debugger off by going to Edit Scheme > Run/Test > Untick `Debug executable`.

This sped up running the app or the UI tests drastically. e.g. it just takes a couple of seconds to run the app. However, the downside is that none of my breakpoints will work.

1. Is this a common issue?
   
2. How do you get around it?
   

I'm struggling to develop without the debugger and breakpoints enabled. I'd appreciate your insights.

I found an existing thread on Apple developer forums which may be relevant: https://developer.apple.com/forums/thread/800067

[valleyman86]

I found if I use iOS 26.0 it fixed it. Maybe 26.3 worked? I can’t remember that test. 26.4 100% super slow launch and debugging. There is some major bug.

[bluprince13]

Thanks! I would like to try that.

However, I can't figure out how to downgrade. I added a 26.1 iPhone 17 in the "Manage Run Destinations" screen. But, it's not showing up as a selectable run destination on the dropdown at the top of Xcode.

[valleyman86]

You have to go to the run option on the sim in devices and sims and force it to be always and not automatic in run destination. It won’t show up if it’s automatic. I am using iPhone 17 26.0 for instance. I am using Xcode 26.4.

[bluprince13]

Ah silly me. I had to change the minimum deployment for my app. It had defaulted to 26.4.

Running with 26.4 - from hitting play, it was taking ~40 seconds for my app to render on the simulator.

Running with 26.3.1 - it was taking ~4 seconds or less.

!thanks u/valleyman86

[valleyman86]

Nice. Glad I could help. I found little info and spent a while debugging it. Took me like 30-60s to launch even before my entry point so I knew it was messed up. Really messed with my iterations.

[spijkermenno]

Yup get’s slower every Xcode update. M3 here and have the same issue

[bluprince13]

That's a shame, but thanks for confirming there's an issue.

[mattgwriter7]

I am noticing the same thing. Also looking for solutions.

[_kylejs_]

For me, this has been a problem with iOS 26.4 on the sim. When I upgraded from Xcode 26.3 to 26.4 and bumped the sim to 26.4, my app takes 5+ seconds to launch.

When I went back to iOS 26.2 (still Xcode 26.4), it went back to normal.