Repository Manager and resource Properties Performance

Hi. I am creating a repository manager for a backend document management system and there are some major performance issues at the moment.

Each document has 40 to 50 or so metadata properties and values associated with it. When the KM Explorer through the portal is rendering the resources of a folder from my repository manager the KM framework seems to be calling the GetProperties for each child resource in the folder.

For our application this executes a web service call to the document management system to get the meta data properties associated with the document. This call takes approximately 2 seconds to execute, so a folder with 30 documents will take at best 1 minute to render. It's actually taking much much longer than that at the moment.

Any ideas on how to get around this? The only thing I can see at the moment is to implement a cache to store the metadata of the documents on the portal. What are the limitations implementing such a cache?

Thanks,

Scott