Compilation taking twice as long in UE5: Number of processes being limited?

[neofuturelabs]

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UE5 C++ Compile Time is Substantially Longer

I’ve upgraded a medium size project to UE5 and we’re seeing substantially higher build times. I’m controlling for as many variables as I can and still seeing significantly worse performance in apples-to-apples comparisons to UE4. I’m opening the same project in both versions, using Visual Studio 2019 to compile, setting build process count to 22 (12 core / 24 thread machine), and unity builds are enabled. I’m observing two undesirable aspects, one of which seems like a serious regression. UE4:…