... maybe DAZ… um…. screwed up DAZ Studio. LOL
and… maybe you need to update your machine?
or try clearing your cache, clearing your cookies and restarting your browser LOL
It will still use the same amount of memory, but your new machine will be able to handle it. 
Seriously, because the Gen4 figures were not originally made for DS4. The Gen4 figures call up morphs before they load even if you did not inject the morph. Depends on how many morph packages you have installed, therefore the size will vary.
Try loading the Gen4 figure in poser, inject all the morphs and save it. Make sure that Poser is set up to create PMD files, which makes the figure a lot lighter. Then load this figure in DS4, it might help a little, especially when you load more than one figure at a time as the PMD will only be called up once no matter how many of the same figure you load. I’m not a DS user, but I assume DS supports PMD files, if not, well, I’m afraid you’re screwed and not in a good way… LOL
Alternatively, if it’s really bad, start removing inject packs, except the important ones, for example Morphs ++ and Elite morphs, which would reduce the size of the figure.
Hope this helps.