Ashley
It occurs even if everything except the wall3d sprite is deleted from the capx, but 9408 images is a lot.
aridale
Why not do your own animation loading?
You're already using a trick to do pseudo3d, so another trick shouldn't be too bad.
You can't add frames at runtime but you can load a different image into a frame. Just loop through the frames to load them. You'll still have to have animations for the wall3d sprite to be able to replace. That will be the limit of how may different wall textures you can use per level.