MS Access – is it time to upgrade?

I develpoed a database that has 18,000 records with a one to many relationship to a table with about 7,000 records. The data is on a network server running Windows 98. The main form is two tabs and 100 controls, including 15 combo boxes. Problem is that unless you’re the first person to log on in the morning it can take up to 6 minues for the main form to load. Most workstations have 64 – 128 MB RAM. The front end is on each computer and the data is on the server.

On my computer with 256 MB RAM, with the data on the same machine as the front end, it takes 2 seconds for the main form to load.

Question: Is this a server/network problem or do I really have to simplify my main form, or do I have to dump Access and use another database?