Provide a Boolean option to direct SETUP to store or use extracted updates in a folder - perhaps "UpdateCache". The source of the update can be online, WSUS, or the UpdateSource folder as it is now. If SETUP needs to extract an update, it is stored in the UpdateCache folder. If the update is already extracted, SETUP does not extract it again and uses the extracted version already in the UpdateCache folder.
Because each source (e.g., online, WSUS, or UpdateSource) can have a different set of updates available, metadata is needed to track which extracted updates are valid for a source. There can be up to three different sets of updates in the cache - one for each source (e.g., online-SP1-CU4 & wsus-SP1-CU3 & updatesource-RTM-CU6). However, there might be one common current update for all three sources (e.g., online-SP1-CU4 & wsus-SP1-CU4 & updatesource-SP1-CU4). There can be two sets as well - one different from the other two.
If a newer version of an update is cached, setup should update the metadata. If there are no sources referencing an extracted update, it should be deleted. For example, if RTM CU5 is cached from a new update place in the UpdateSource folder, remove any metadata for this source from other extracted updates, if present. Extracted updates left without any sources are deleted.
It is safe to clear the UpdateCache folder as it would be reloaded as needed.
If the UpdateCache option is not provided, SETUP ignores the UpdateCache folder.
Administration could also be improved if an online update can be used to populate the UpdateSource folder. I can manually get the updates, but it would be nice to have the setup do this for me. Allow us to place the extracted update into the UpdateSource folder?