Our NIPR machines aren't the greatest, but we didn't see issues like that upon Win10 upgrade. I can reboot and be up and running in 3-4 minutes. It's probably a function of the RAM installed in your machine. FWIW, Microsoft stopped supporting Win 7, so DoD really didn't have any choice.
Its very hardware-dependent. In my DH tour, the NMCI assets were relatively effective, and I could get work done. Now that I'm at a shore command, it's terrible. Our notebooks here are the same models my fleet squadron had tech-refreshed 2-3 years ago, which were then replaced again in late 2019. They may not have enough RAM, but they definitely don't have the HDD bandwidth to support Windows 10 or the performance-crushing bloatware that is McAfee AV.
I have to reboot every time I bring it home or RAS/VPN won't work. Can't get any nerdery done in Excel without a few daily app crashes.
Maybe NAWDC has fleet-like priority/assets? The newest notebooks are silver with sleek low-profile docks. The dark gray notebooks were before that, and I rock a black HP, probably from before I winged.