I have a VB COM client in an STA making lots of calls to a in-process free-threaded C++ COM object. I am stuck with thisthreading model since I cannot change theVB COM client tobe free-threaded(due to limitations of VB) and the COM object must be in an MTA since it has worker threads that need to access it asynchronously (these requests would be serialised if object in STA).I am concerned about the marshalling overhead between the 2 apartments, since the client is making a large amount of calls to the COM object. Since the apartments are both in the same process, can I assume that the overhead is insignificant? I assume that it would be less of an overhead than if the apartments were in different processes.Any ideas would be greatly welcomed. Thanks :-)

You might get better responses somewhere on the MSDN forums :) I'm guessing that the majority of readers in the Technet forums are administrators / engineers like myself, and not full-time coders.Cheers!Trevor SullivanSystems EngineerOfficeMax CorporationTrevor Sullivan Systems Engineer OfficeMax Corporation

HiIf your not sure where to post your question, go to the following forum and describe the question you have. Someone there will direct you to the proper forum.Where is the Forum For?Hope this helps. Ronnie Vernon MVPForum Moderator