Same PC, same hardware, but different results when running Win 10 Pro or Win 11 Pro?

[Oldtimer]

Newbie alert... There may be answers to this on the forum, but I haven't been able to find them. I tested a Lenovo L13 Gen2 Yoga today. It came with a fresh installation of Win 10 Pro. I ran the Passmark tests, and ran the tests again after upgrading to Win 11 Pro. The overall score dropped from 1943 on W10 to 1609 on W11. I was under the impression that Win 11 would run more effeciently on older hardware - but most significantly: the CPU score dropped from 6681 to 5175. Other results were more or less the same (memory and disk scores a bit higher on W11, 2D and 3D graphics scores a fraction lower compared to W10)

Same laptop, same version of Passmark (11), only difference was the OS. I can't understand why the CPU score nosedives while running W11 OS . Any thoughts are welcome.

[David (PassMark)]

CPU result shouldn't have changed much (if at all), in theory.

But if this was a new upgrade then it is possible Windows was still downloading patches in the background, or upgrading apps.
It is also possible that updated CPU micro-code was applied. There was a bunch of this done for security reasons recently, but some of them had a performance impact. Could also be something more mundane, like you are running on batteries now and mains power before, or thermal throttling.

[Oldtimer]

Thanks. Yes, I ran the Passmark tests an hour after upgrading to Win 11, so it might have been too soon, as you suggest. Besides that, everything was identical, running on mains power. I was trying to establish a baseline before swapping the (sometimes) crappy in-house Lenovo M.2 256 GB to a Kingston Fury 1 TB. The reduction in CPU score left me somewhat bemused. Next time, perhaps wait 24 hours after upgrading?

[David (PassMark)]

You can force updates to happen from the Windows update screen.
But it is also good practice to wait several minutes after booting the machine as well. There is a huge amount of stuff that runs in the background on Windows machines now, hard to avoid it all.

[Tempak]

Windows 11 comes with CPU core isolation enabled, which may cause significant PC slowdown.
This settings is also available on Windows 10 but not enabled by default.

Follow this article, especially first advice, then do retest your PC:
https://support.microsoft.com/en-us/...6-ff6f3f474613