Whew!. Your .obj files of unshaped leaves vary between 4.69-13.5MB! Whole Carrara complete trees with shaped leaves are in the 3-14KB range. And the leaves can be shaded with adjustable levels of transparency. You sound like you must spend a lot of time waiting while things render--is the end result really that good? Can we see one of your examples please. Perhaps someone can emulate in Carrara and quote file sizes and rendering times.

bwtr