On Capture NX-D, it is pretty slow, as all the Nikon software seems to be, but it does depend on the computer. On my current cheap Win 10 laptop it's usable. Slow to load initially but OK once it's going, though both it and the earlier Capture NX-2 are slow to do conversions too. On my traveling Win 7 "Netbook," which is truly minimal, both are essentially useless - useable in an emergency but best avoided.
I did have one issue with NX-D in windows 10, that one of the updates did not install properly, though it seemed to be working and gave no error messages, and the previous version had gone fine. It would load but nothing would come up when I tried to run it. It was a permission issue, I think. Although I have set up with as a single user and administrator, Windows 10 does not actually give full admin. status even if you're logged on as a user/administrator. I solved the problem by creating an actual Administrator account. When I logged into that, it installed properly.
