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.