Dynamic code generation and memory management techniques are provided for component object model (COM) objects with corresponding representations in script code and native code. A browser component can receive script code including the code representing the COM object and a marshaling component is provided that marshals, based on a request for native code representing the COM object, the code representing the COM object to the native code based on a pre-constructed intermediate data structure. The pre-constructed intermediate data structure, such as a virtual table, is pre-constructed based on a dynamic type representation associated with a prototype of the COM object and cached for re-use by the marshaling component. Other embodiments provide finalizer support for memory management of COM objects having script and native world representations including an implementation of a two-phase commit protocol that enables efficient and conservative recycling of objects and associated memory.