Performance difference Win 7 vs Win 10?
Somewhat by luck, I've got my hands on two systems for a short time, one Win 7 and the other Win 10. Both have a GTX 1060 FE card. But when I run hashcat 3.6.0 on both, doing MD5, I'm getting quite a bit different speeds. The Win 7 is doing 9000 - 9500 MH/s, while the Win 10 is doing about 5600 MH/s. The Win 10 system is newer.

Why such a big difference? Does the OS really matter that much? Both are running the latest drivers.
You should be more specific about what you are trying to run.

... or are you talking about just benchmarking with -b ?

If you do not just run "hashcat -b", but some other types of attack, e.g. wordlist, there might be also other factors you need to consider... like HDD/SSD speed, RAM etc

The operating system and operating system version in theory shouldn't matter at all...
I'm running a mask attack, from different points in the same hcmask file I generated using PACK. (I deleted some from one copy then started hashcat.) All the masks are 10 characters, not that that should make a difference.
I've done some more experimenting and I'm convinced there are other factors that determine speed besides the video card and hash. When I upgraded my main cracking system to the 1060 card, I took my old card, that got about 2600 MH/s (MD5) and used it to upgrade my TV computer (use it for watch shows) and continued the cracking job I was doing there. Last night I was getting about 2100 MH/s, and tonight I got, with it idle (no shows playing) about 1100 MH/s (a restore on the same run).

It got me thinking about time I tried running a hashcat mask attack on my GPU and CPU at the same time. While I gained from the CPU, my GPU hash rate fell far more than what I gained from the CPU. So I killed the CPU job and my GPU job went back to it's former rate. So, while getting 1100 MH/s, I checked my CPU usage (procexp) and it was like 95% idle.

The one thing I did note is the hashcat hardware monitor is showing my older card at about 37% utilization, so that partially explains the lower rate. I checked on the windows 10 1060 card computer, and it was around 50% there. I resumed the other 1060 card (windows 7) and it's about 91% utilization. So it's not resuming that's doing it.

Anyone have any ideas what the problem could be? Obviously, there's something at play that can have a big effect on your hashrate besides the card, the hash type, and the attack type.