There's an interesting thread on the MSDN forums regarding DMF performance or more accurately the overhead of having policies on the system. If you're interesting in using policies on your system and have thoughts on an acceptable overhead go post your thoughts to the forum.
Personally, I'm in the camp that believes DDL is not restricted to the same performance requirements as DML. Granted there are cases where you need to create a number of objects "on-the-fly" and in a certain amount of time. Think of a data loading process where the data is first loaded into "temporary" tables. You want those temporary tables to be created as quickly as possible. But will it really matter if it take 10 or 30 seconds rather than 1 second? I don't think so.
But let us know what you think.