As I said, I'm not doubting your problems. You should report them to DAZ, though.

I just loaded two more copys of M6 for a total of five and clothed them, too. No difference whatsoever in clothing loading times. It was 5 seconds or less.

OpenGL still fully responsive.

I'd never ever be able to do that with standard 3rd or 4th gen DAZ meshes, especially Vicky 4 with all her "joint-smoothing-magnets" dead weight.

Only my own "super-optimized" polygon reduced weightmapped 3rd gen meshes can usually do that, but even these slow Poser down after loading 5 or 6 naked figures.