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2023 Mac Pro M2 Ultra: Large Losses in CPU and GPU Performance; Rebooting Recovers temporarily

UPDATE 2023-07-18: 2023 Mac Pro M2 Ultra: Sleep/Wakeup Causes Drastic Loss of Performance for both CPU and GPU
UPDATE 2023-08-02: (tentative) it appears that this bug was fixed in macOS Ventura 13.5.


As discussed in 2023 Mac Pro M2 Ultra: Unexplained Large Losses in GPU Performance, large losses in GPU performance take hold, which only a reboot corrects.

But degraded performance is also happening with CPU performance. As with the GPU, a reboot corrects the issue.

Compare the CPU performance before and after rebooting. In both cases, there was no other significant usage of CPU time by any other processes.

With a single CPU, as shown, the performance difference exceeds 50% — 1024K/sec vs 1580K/sec. That is a HUGE difference, like having M2 Max instead of M2 Ultra.

What is going on? I want what I paid a huge premium for, not a science fair project that works some of the time.

Could there be downclocking related to heat or some such?

macOS Ventura: wildly differing CPU performance, degraded vs rebooted
macOS Ventura: wildly differing CPU performance, degraded vs rebooted

Anon developer writes:

Maybe your workload got shuttled off to the secondary die. Just a hunch. It definitely looks like a bug though.

MPG: if all CPUs are in use, then there should be no difference. It’s as if everything got downclocked.

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