To minimize the GPU overload, we have limited the viewport clipping to Camera views. It has not effect on perspective viewports.
Our idea is to use minimize the view updating as much as possible. We introduced this feature many years ago, when 3DS Max was very different, and the performance impact was not very noticeable.
But with the recent Max versions, Nitrous, and the new GPUs, the scenery has changed. There is a noticeable performance hit, if the Forest object must be updated in the GPU, with each view change.