This problem happens on c4d plugin, not sure if max has the same problem.
Here is how you get this problem:
1. Build any scene with morph and camera animation over 1000 frames.
2. render the first frame, check status bar, you'll see the preparing time for this frame nearly less then 1 second.
3. go to frame 1000, only render this frame, you'll see corona takes minutes to prepare the same simple scene.
The time for preparing your scene keeps increases with each frame.
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made a search with google, seems I have to cache all the morph animation before rendering.