OK. I figure this out: I couldn't understand how a 1/2 gig database could be "live" constantly and didn't need to be refreshed.
So I ran a query, changed a record in the database, ran the query again and the data was updated. I was surprised.
What happened was when I originally created the database I had imported the data, then ended up doing some research and creating linked tables instead and deleting the original tables.
I did a compact and repair and now the MDB file is small.
One thing I don't understand is why running a Crystal Report against an AS400 database is slow, but running the same Crystal Report against Access tables that are linked to the same AS400 database is lightning fast.