Now, for us to test this techniques application you must add a Noise modifier on the Plane (Fig.14).

Fig. 14
You should notice that the Noise is acting only on the selected area. Depending on the situation, this may or may not be desirable. In the case that it's not desirable and we need it to be applied over all of our Plane, we just have to apply the Poly Select modifier before the Noise, without changing any of its parameters. This will end up cleaning all of our actions above it, making the Noise affect all of our Plane (Fig.15).

Fig. 15
In case the subdivision level on the first or remaining levels is not enough, we can go back to the MeshSmooth modifiers and raise the Iterations value, but beware! This should be done carefully. You should always save the scene before doing it and you should have backup copies, because having too high subdivisions can break your computer, especially those with low RAM memory (the minimum recommended by Autodesk to 3ds Max is 4GB of RAM).
Another quite viable alternative is adding a TurboSmooth modifier above the Poly Select, or even a MeshSmooth modifier, and using the Render Iterations (Render Iters.). You can play with Iterations x Render Iterations values; everything may vary according to the scene's needs (Fig.16).

Fig. 16
You can see that the subdivision level in the center is way bigger than on the extremities. Here you can see an example without Poly Select (Fig.17).

Fig. 17
As I explained, the Noise will act only upon the selected area from our Vol. Selection. On the other hand, the TurboSmooth, as it was said before, doesn't work with selection. But if instead of working with the TurboSmooth you're using a MeshSmooth, then, differently from before, we need to leave the Apply To Whole Mesh option on so that it doesn't act only upon the selection.
Now our tool is complete. You can try it by moving the camera to see how it will turn out (Fig.18 – 19).

Fig. 18

Fig. 19
All we've done so far is enough to optimize a lot our scene, but there's still more we can make. We have a whole geometry that doesn't show in scene and that stays behind the camera; in specific cases we may need this part (for reflexes or other specific needs) so you just have to ignore this last step. This hidden geometry could be removed from the scene to leave our project even lighter, so let's see how we can do this.
Add the Slice modifier under the Poly Select modifier and check the Remove Top option (Fig.20).

Fig. 20