I'd encourage you to stick with Ziva cloth because it's more likely to give you the right result. The time spent tweaking ncloth settings can just be spent letting ziva cloth do it's thing. ncloth is a general purpose cloth solver which really has to be massaged to work for fascia, where ours has been designed with this purpose in mind.
Ziva cloth also has lots of room for optimization, which will eventually happen in future releases.
In the meantime, if you can keep the point count down, that will help you with speed. In areas where you're not so concerned about detail loss, you can decrease the resolution of the mesh.
Some other ideas for speed. Split your fascia up. Try doing an upper body fascia and a lower body fascia. That way you can iterate on one at a time, and if you have the capacity, solve them in parallel.
Some other helpful things for the fascia pass. If you're running collisions, key gravity from 0 to -9.8 over a few frames, so it gives the solver a chance to resolve collisions. Or just turn gravity off.
I've found turning the frames per second attribute down to something like 4 (from 24) can be helpful too for resolving collisions.
Keep attachment stiffnesses relatively low if you have the cloth at default settings. ~1x105 has been about as stiff as I've needed to go. Same goes for collision stiffness. Higher values can introduce instability
If you're super concerned about speed, you can always solve your fascia as a tissue. Turn collision volume off on the fascia if it's a closed mesh