The 3ds Max 9 SDK have added new classes and updated existing classes to introduce significant performance, functionality and, especially, memory management improvements. This means that, to achieve optimal performance of your plug-ins, you will need to visit the code of your existing plug-ins and consider making changes.
Upgrading plug-ins built using earlier versions
Upgrade information is organized under the following topics:
New Features and Other Changes to the 3ds Max SDK
The following is a list of what else is new as of the 3ds Max 9 SDK: