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2023 Mac Pro M2 Ultra: Large Losses in GPU Performance Require Reboot

UPDATE 2023-07-18: it’s not just degraded GPU , it’s degraded CPU also. This suggests a systemic problem.
UPDATE 2023-08-02: (tentative) it appears that this bug was fixed in macOS Ventura 13.5.


First off, I see high GPU usage while the machine is doing nothing useful (idle). I don’t know if this relates to the major performance losses I am seeing. It appears to be a macOS bug that eats up GPU cycles (somewhere!), because no applications show up as using the GPU, I’ve quit every app except Finder, but only rebooting restores full GPU performance.

Major Photoshop performance losses — apparent bug

In running various Photoshop benchmarks, I am seeing a huge variation in performance of up to 66% slower than it ought to be.

This variation is not so much a variation as toggle between full performance and degraded performance. That is, when degrade, it remains degraded and is consistent in speed, ditto for when not degraded.

$10K for a machine that crashes if hardware in widespread use is attached, and also degrades itself to 2/3 to 1/2 GPU speed when it’s otherwise “working”.

I want what I paid for, not a science fair project.

Apple marketing claims of 200% or 300% faster on all sorts of things. Did they footnote that as “* shortly after reboot and only temporarily”?

macOS Ventura with M2 Ultra is the new Windows 98... not working right? Reboot!


Below, this is what I am seeing.

Reboot, and performance is terrific. But after a while speed degrades, even when no other applications are running. Performance losses are up to 66% slower than after reboot.

macOS Ventura: wildly differing performance GPU performance bug
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