Don't bother, 32x cubes with the same volume as a number of 64x cubes lag just as much when clearing and loading.
My 32x modter cube planet has only 2,500 modter cubes and it freezes the game for half a minute (a VERY long time) when cleared.
I've also ran tests using solid chunks of modter cubes with the same volume, one using 32x, the other using 64x, and they both lag the same when cleared.