Lower passmark scores since win 10 fall update

[cjoooooooo]

Previous to the fall update in September I benched my pc. After testing my pc the other day I noticed my cpu bench and memory bench were below normal scores.
Most notably single threaded performance. It's down by 100, which is too much to be considered margin of error.
I decided to test with a fresh install on a different drive to see if It was system related and sure enough my scores were back to the original norm.

I proceeded to test by cleaning out services and junk, virus and malware scan and just about everything I could think of to see if some background interference was causing the dip in score.

Nothing has worked.

I tested cpu-z bench also and the results were less obvious but still favouring the fresh install.
Tests have been repeated multiple times.
Might try a 3dmark test next to see if it affects gaming.

My question to anyone who might know is, could this just be a compatibility glitch with some type of registry change or framework?

[David (PassMark)]

You didn't mention what hardware you had, nor what the actual scores were. So it is hard to judge how significant a change of 100 is. I suspect it is smaller than a 5% change.

When you are looking a the cause for very small changes like this, you need to have a very careful measurement methodology. Window's background tasks which run from time to time can easily account for 5%.

One way to improve accuracy is to run each test 10 times and take the average, or the max. This is an options from the preferences menu in PerformanceTest.