I also think clothes contribute morphs, not just characters.
if you rename the \data\DAZ 3D\Genesis 8\Female\Morphs folder there are no morphs left. G8F will load with no morph, also no hidden morphs and no cloth morphs and loading times are of course extrem fast.
So a workaround would be to rename your Morphs folder and create an empty Morphs folder and just copy the morphs you want into it. But that is a lot of manual effort, to much in my opinion.
Else moving G8F to an SSD could be an alternative.