1 hour in 10/04
In October 2004, with about 120 passengers on board, we took about an hour at the border northbound and arrived in MTR within a minute or two of the scheduled arrival time.
The border crossing event on trains here in North America is certainly primitive compared with Europe.
One exception is SEA-VAC northbound, where customs/immigration/terrorism is checked at VIA's VAC station thanks to the intervention of the Congressman who started that service. That helps a little, if BNSF can keep its freight trains out of the way.