What you are planning will not affect the framerate at all, I'm currently using vec_for_vertex to get each and every vertex position on my character-models (for an ego-shooter, multiplayer) and converting them to relative values, calculate frame positions angles... (simulated bones
) and then using vec_to_mesh to aplly these calculated vertices onto my models, this worked fine with 6 characters (a 1200 vertices), no performance lost