Slow launch of app on iOS Simulator 26.4

Same here.

Updated xcode & simulator yesterday and out of sudden ios apps when started show a white screen for seconds before the main application screen (i.e. a splashscreen) appears.

Added print() to trace but it looks the delay happens not in user code. Looks like loading libs during the startup process takes ages before user code starts running.

Did some more testing.

The white screen/delay only happens when the app is provisioned for debugging and started for the first time in the simulator.

When i terminate the app and start it on the simulator again (w/o debugging from xcode) all went smooth. No white screen, no delay.

So it looks like there is some kind of debugging/first run overhead that causes the delay aka white screen (system launch screen) to be visible for that long time.

I'd like you to try something — go into your scheme, and uncheck Debug Executable from the Run tab. When you click Run, Xcode will run your app with going through the process to attach LLDB. Does the launch performance after this look more like you're expecting?

If so, we'd really appreciate getting diagnostics so we can look into the root cause of this slow down. Add the following to your ~/.lldbinit file, and the restart Xcode to ensure this is enabled:

log enable gdb-remote packets --timestamp -f /tmp/log_packets.txt

Before you launch your app, run the following in Terminal:

sample lldb-rpc-server 60 --wait -file /tmp/sample.txt

Attach both of those files that those commands placed in /tmp on your bug report, and let me know here when that's done. I also suggest removing the log line from ~/.lldbinit so it's not always logging debugger packets.

@Code4Food, it'd be helpful if you could run the same tests and collect the same data, and attach them to your own bug report. Please post the FB number here so we can locate it.

— Ed Ford,  DTS Engineer

I'm seeing it take 1-5 minutes on launch on Xcode 26.4 (most often around 2m). As suggested, when turning off "debug executable," it launches as expected. FB22353872. I've added the requested traces. This also happens when running unit tests via Cmd-U (which is also configured with "debug executable").

Also reproducible here, without debugging start is a few seconds, with it takes over a minute. FB22365004

100% repro here. Xcode 26.4 is unusably slow and I am having to downgrade. FB22366086

Part of the problem here might be general system performance if the system is occupied generating the dyld shared cache for the simulator runtimes.

To ensure that the caching has completed, please run simctl runtime dyld_shared_cache update --all (which will terminate once all caches are available). Caches are invalidated if you update to newer versions of macOS.

If the issue occurs while the cache is being generated, it probably represents an I/O bottleneck. If the issue exists with the caches available, then we have something more critical in the OS to look into.

Please confirm if you are seeing the issue with specific debugging tools enabled (eg: sanitizers, malloc history, etc).

➜  ~ /Applications/Xcode.app/Contents/Developer/usr/bin/simctl runtime dyld_shared_cache update --all
Updating dyld shared cache if needed for runtime: iOS 26.3 (26.3.1 - 23D8133) - com.apple.CoreSimulator.SimRuntime.iOS-26-3.
dyld shared cache is usable at path: '/Library/Developer/CoreSimulator/Caches/dyld/25D2128/com.apple.CoreSimulator.SimRuntime.iOS-26-3.23D8133/'.
Updating dyld shared cache if needed for runtime: iOS 26.4 (26.4 - 23E244) - com.apple.CoreSimulator.SimRuntime.iOS-26-4.
dyld shared cache is usable at path: '/Library/Developer/CoreSimulator/Caches/dyld/25D2128/com.apple.CoreSimulator.SimRuntime.iOS-26-4.23E244/'.

But no changes to the startup time. Regarding configuration: