The memory requirements of an ObjectARX application are different from those of AutoLISP. On the one hand, the data structures employed by C++ programs tend to be more compact than AutoLISP lists. On the other hand, there is a rather large, fixed overhead for running ObjectARX applications. Part of this consists of code that must be present in the applications themselves; the larger part is the ObjectARX library.
Some ObjectARX global functions allocate memory automatically. In most cases, the application must explicitly release this memory as if the application itself had allocated it. AutoLISP has automatic garbage collection, but ObjectARX does not.
Failure to release automatically allocated memory slows down the system and can cause AutoCAD to terminate.