It should be possible to open the graph connection with a Artifact Unique Id that, based on that, load a local cache.
This local cache should use a really fast storage engine (redis) just to avoid OutOfMemory Exception.

The cache should be cleaned during close connection.

Probably the Artifact will hold a list of its created nodes and links (try to use the Graph itself to hold this data on a special context related to Artifact: ArtifactContext).

Important Notes: The cache should be created even for excluded artifacts, 'cos it will help to execute the DeleteLinks and DeleteLinkedNodes. The cache is shared for all graph threads.