@JoeRowell
In addition to arnel's advice, you could try a Compact and Repair on BOTH the new Front End accdb and Back End accdb to see how much bloat you can remove.
That said, the free SQL Server Express version has a 10GB size limit, so it's a good option.
However, migrating from an Access BE to a server database BE can introduce a number of problems that will require design improvements in an Access FE.
Other considerations include much better security options with a Server-based BE.
