Fusion isn't all that intensive, IMO, but having enough RAM and an SSD sure makes a nice difference. I'd recommend at least 12gb of RAM for Windows 10. Lots try to get away with 8gb, and it just isn't enough in my opinion. The W10 work station I am on right now is using 9.5gb of it's 24gb of RAM, and I'm not doing any CAD/CAM. If I open a few models in Fusion it takes up another 2gb or RAM.
I have four MacBook Pro's though, and even my oldest one (mid 2011) still runs great. They all have 16gb of RAM and SSD's though.