hello!
I’ve notice that with time, mediabay loading too long. I’m talking not only about sample folder, also i mean Presets (vst, channel strip,Channel editor & etc.)
and i know its loooooonggggg story bug. But, maybe each of us have some tips & tricks to speedup, lets collect them all in one place 
found one little solution with Sample folders(users) you need to rescan them sometimes.