Performance deteriorating when executing multiple commands that modify the cube

Recently I was pointed to "SSAS personalization extensions" as a way to build user-defined groupings (sets) into my cubes.

I've noticed a limitation when the number of user-defined objects increases.  The performance gets incrementally slower as more commands are executed.  The commands in this case are executed via AdomdCommand (part of Microsoft.AnalysisServices.AdomdServer).

This same issue is reproducible outside the context of SSAS personalization extensions.  Even in SSMS if you execute the following a whole bunch of times with changing SET identifiers, you will see the performance decrease.

CREATESET [Sales Budget and Activity].test100
as {[Branch].[Branch Code].[Branch Code]};

The first 100 are created in a total of a second but it takes about five seconds to create the next 100 and ten more seconds to create the next 100.  Basically it takes 16 seconds to create 300.   You get the idea.

Is there a good reason for the deteriorating performance?  Is there a way to create these session objects in bulk (I don't see a transaction or anything that might join together multiple commands)?

Thanks in advance,

David Beavon