Garmin slowness with updating maps

I’m currently at my mom updating her Garmin Nuvi navigation unit.
All the maps have been downloaded, and now I’m in the process of putting them on the device, but the software takes a while.
At first it’s building index files, and when that has reached 100%, it’ll still take a long while before it continues with building traffic files, unless you choose a small map, but you can’t do it piece by piece. It has to be done in one move. And apparently the building of the index files can take up to and over 1 hour.

So, be forewarned, if you want to update your Garmin, let it work for a long while.