I highly doubt the 2D animations have anything at all to do with this. Speaking from experience with programming with DirectX (not openGL though), all that happens to change an animation frame is that a simple, single rectangle, made up of 4 ints, is altered slightly, with this probably only 2 ints would change if the animation frames are horizontally or vertically adjacent in the texture files which I think they are. This rectangle effectively cuts out the relevant piece of the texture to render it in place of the last. Keep in mind everything else will have a rectangle too to divide it\'s texture out of the file, and these all get processed each frame. Also, each texture needs to only be loaded in graphical memory once, so the memory space taken up doesn\'t even need to be duplicated for each block.
So, unless the game is extremely horribly coded, 2D animations will have practically no impact whatsoever.. unless you\'re playing on a 1980s calculator of course.
Werty would also be correct in saying that block faces aren\'t rendered if there\'s another block touching that face (occluded), you can see that easily by flying through your ship in build mode. i.e. When you\'re inside blocks, you can see through any adjacent attached ones.