I use a large entity array with this dimension ENTITY* ent[16][16][3][3];
As I use terrains there is no need for ent_clone before the vertex deformation. I tried both, deforming vertices on models with ent_clone and deforming them on terrains without ent_clone(which is the faster solution).
One Chunk has the size of 3 * 3 = 9 tiles. There are 9 Chunks loaded in the level, so there is a permanent amount of at least 81 terrain entities. All of these terrains are deformed with ent_setvertex.