Whenever I hear about MS Access, I shudder. Nothing to do with the program, but how organizations use it.
MS Access was never designed to operate well over a network. It can operate just fine over a relatively high-speed, low latency Ethernet network, but it performs very poorly when run over a wide area network which usually includes a significant increase in latency.
As my day job involves helping clients move data centers, with almost every move we hear about issues of slow performance. Very often it is tied to a "critical" Access database that was never captured as a key application but has now been moved to a remote data center. Performance is poor, and the client basically has two choices: 1) Move the Access DB back to be local to the users, or 2) Migrate from Access to a full-fledged SQL Database with a front-end application residing on the user's desktop.
Grumble, Grumble, Grumble. Current client is dealing with this right now from our move in November.
It is a great single user, write a database to do what YOU need, but never intended to be a robust, multi user, remote database.
We used to have an application that ran on an Access backend, but only the local, laptop version we used when traveling. The data was then sneaker netted (security reasons) to an Oracle database that did the heavy lifting.
The whole application (laptop and mulituser around the world) not runs SQL Server.