Has your .max file ever take an excessive time to open without you having added that much amount of geometry? Did your file got so large and uses up so much memory that it takes ages just to save.
This can happen when you merge other .max files into your main file, creating lots of trackview nodes.
To delete these issues run the following line of MAXScript in the MAXScript Listener (image below) and make sure it's all on one line!:
t=trackviewnodes;n=t[#Max_MotionClip_Manager];deleteTrackViewController t n.controller;gc()
How do these trackview nodes get in your files?
There was an issue with an old version of 3ds max that caused these nodes to be added to scenes after a new file is added (merged), that problem has been solved in newer versions.
However, if these nodes are in an old file they will not be removed automatically. And if you merge anything from a file that has lots of these, your main file will have them also.
How to prevent this from happening
Unfortunately, there is no quick solution. If you have an old library of assets that you still use, you will need to check if these files don't have nodes in them. The best solution would be to go through all these files and run the MAXScript to make sure they're all clean.