It is usual in MAX 2016 and Forest pack version from 6.07 beta, 6.08 beta and also 6.09 full version.
It is hapening in large scene with more forest object included and displayed as point cloud. We are using network licences.
When using one fullscreen viewport it is OK. When you switch to 3 or 4 viewports mode in max, you have like 70 percent probability of an almost on minute freeze before you can work again. It is caused by point cloud preview of forest objects.
As we have experienced this starts usually after scene save, so usually 10-15 minutes after opening of scene.
I will try to find some small scene and send it to support.