Counter Strike renders every frame because it renders a world. And CS and all the 3d games almost always have some kind of animation going on.
Where as if your only rendering 1 model to be used as it's own object. Then you only need to render when a key moment comes up. If your interpolating motion every frame; not every frame has enough change to make it worth while, especially an idle animation. Also not all objects need to be rendered every frame. One way to improve performance is to have background objects update there 3d image at 24fps. This leaves more performance on the active objects.
Your strength here is that your in control of the updates of when the sprite 3d object needs updating. And this opens up a world of opportunities to provide 3d/2d scenes while maintaining fantastic performance and fantastic imagery,
Also sprite sheets use up large chunks of memory. Where as a 3d object uses far less. 3d objects use more GPU as cost instead of memory.