The Empire Builder had pretty bad performance a few years back due to the Bakken Oil Field boom in MT/ND. They've double tracked a lot of the line since then, and the price dropped, so it's not as bad as it used to be. It's been pretty good the last couple years. When I took it in May, it was maybe an hour late to St Paul and on time back to Portland. A delay can still happen, though. But a delay can happen on any long-distance Amtrak route.