The Backup time is all depends on the size of the Lightroom Catalog.
Please try and create new catalog, import your new images and then try to backup with the optimize and test integrity boxes checked.
Let us know if that helps.
Ok - I have only ever used one catalogue so I guess this might be the problem. Unfortunately I don't know anything about catalogues, creating new catalogues, how to manage them and why I need to work like this - can you help me out?
Sent from my iPhone
To create a catalog: Start Lightroom and choose File > New Catalog. Specify where you want to store the catalog, enter a name, and click Create. To open a different catalog: Choose File > Open Catalog, navigate to the location of the catalog you want to open, and click Open.
Hope it helps.