I tried to use an access db over a VPN tunnel and it ran RETARTEDLY slow.
I then used SQL server remotely and it ran fast.
I'm trying to understand what the difference is and can't find any information about how/why they run differently. Any ideas? Know where I could find a resource? Is the difference completely on the application layer of the OSI model?
SQL Server is a database "SERVER". That means it is designed to process data and send the results back to the client that requested it. Because it is only sending back the results of the request, it consumes negligible network resources, and the servers generally are very powerful multi-processor machines with lots of RAM.
MS Access, on the contrary, processes the query on your local client machine (usually less powerful than a database server). That means it has to transfer ALL the data required for processing over the network before it can finish a query.
So imagine a query that joins two 500 mb tables, but returns only a few dozen rows in the result set. SQL Server only transfers the answer over the network, but MS Access requires that a gigabyte of data be pulled over the network.
If it's not practically useful, then it's practically useless.