Significant Increase in Build Times After Migrating from Xcode 15 to Xcode 16

[Dom798]

Hello everyone,

I've recently migrated my development environment from Xcode 15 to Xcode 16 and have noticed a significant increase in build times for my project.

Here's a bit more context:

• Increased Build Time in %: +63
• Xcode Versions: Xcode 15.4 to Xcode 16.1
• System Configuration: Sequoia 15.0.1, 12 CPU, 32 RAM
• It is a large C++ project.

Has anyone else experienced similar issues after upgrading to Xcode 16? If so, were you able to identify any specific causes or workarounds to reduce build times?

Any insights or suggestions would be greatly appreciated.

Thank you!

[fkorotkov]

Do you start a fresh VM for each build? There are some regressions in Xcode 16 which causes CPU spikes:

You can see if that's the case by adding a sleep 180 in your build to let the CPU to calm down for Xcode 16 VM. Then if the rest of the steps in yoru pipeline have the same timing then it's the reason.

[Dom798]

Thank you for your suggestion!

• Yes, a fresh VM is started for each build.
• I’m currently investigating the process manually, triggering the build using xcodebuild clean build. Based on this, I assume the GateKeeper scans should already be complete by the time the build starts.
• Nevertheless, I tried adding a sleep 180 as suggested, but the build time still increased significantly, as mentioned earlier. Unfortunately, this didn’t resolve the issue.
• Since I’m triggering the build manually, I can’t pinpoint exactly where the process is slowing down.

Do you have any other ideas about what might be causing the delay? Any tips on where I should focus my investigation would be greatly appreciated.

[fkorotkov]

Do you see similar build differences locally? Do you run VMs on EC2 Mac instances by any chance? If so, you might want to try do tart run --root-disk-opts="sync=none,caching=cached" for your VM.

[Dom798]

Thank you for the follow-up!

• Just to clarify: Are you referring to building with a Tart VM using a shared folder? If so, the increased build time is even higher in that setup (mounting sources into the VM).

• If you mean a native build, the build times also increased with the update to Xcode 16, but not as dramatically as with Tart builds. Since there is the known regression you mentioned earlier, the increased build times in this case could be related to that.