Hey thanks for your suggestion Mark. I tried converting from PSD to PNG and it didn’t help. BUT!!!!…..
With some tests I found out the very interesting fact that it’s not the resolution of the source media that’s necessarily the problem, its the size of the composition it’s in.
THE TEST: I made a fairly complex 3D animation of 28 duplicates of a 5K image around the Y axis and pre-comped them, collapsed transformations and animated it rotating. It took about 1 second per frame to render.
Then just as a test I pre-comped the base .psd layer (with leave attributes) and replaced all the base layers with this pre-comp. No surprise, it didn’t change the render time.
BUT! when I reduced the size of this base layer pre-comp down to just the area of the image with alpha (mind you I am cutting out invisible pixels but only via comp size, NOT replacing the image file) then went back to the top comp, cleared the media and disk cache, and rendered again, render times were cut in half!
WILD!
LESSON LEARNED: Use base layer comps to crop your footage/images in order to reduce render times!
It would be great to hear if others get the same results.