Xcode 16 performance regression

We recently upgraded our CI from Xcode 15.3 to Xcode 16 and now use the iOS 18 simulator to run our unit tests. We are seeing a large performance regression in our test times (takes twice the time as before).

I noticed a lot of CPU consumption related to the iOS simulator image that I didn’t observe with Xcode 15.3.
Screenshot 2024-10-10 at 10.56.51 AM

I checked also if the issue is specific to the iOS 18 simulator but it also happens when running with iOS 17.5 under Xcode 16.

Any ideas how to work around this?

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We’re also seeing performance regressions in Xcode 16.0. Build and test times take considerably longer on CI, almost twice the time Xcode 15.4 takes.

Once, earlier when the Xcode 16.0 image was released from CircleCI, the same workflow took almost 12x the time of Xcode 15.4. That has since been reduced to 2x, but it’s still enough to force us to stay on Xcode 15.4 for now.

We didn’t try Xcode 16.1 yet to see if that improves the performance