I am trying to do the first program using shaders and I saw a strange thing. Is it possible that the texture access inside a vertex shader has huge time cost?¿ I change the access to the fragment shader and the result is surprising: access in VS 0.4 fps, acces in FS 2000 fps.
Vertex texture fetches are only supported on floating point 32 bit textures with four or one component. You probably use an unsupported format and fell back to SW rendering.