Hey Mark,
Package creation times all depend on the hosts server configuration and how much resources are being used. If your on a server with 1000 other uses and even a portion of those sites are consuming moderate to heavy traffic then it could take a long time for 400MB and in many cases just won't finish at all... It looks like yours is stopping around 9mins.
I have a shared host and packing around 500MB can range from 7mins to upto 18mins. The same size on a VPS I have can be done in 3-4 mins. It really depends on the overall environment.
You might try some of the suggestions on the FAQ related around timeout issues, as in your case you might have to use the directory exclusion filters.