When I saw #8(2) on Sun 4 Dec 2005 at 14:52, it appeared to be moving at a full 79 mi/h and was just under 7 miles (railroad) west of Glenview, where it was scheduled at 15:00. According to amtrak.com it arrived 3 minutes early in Glenview and arrived 16 minutes before its scheduled 15:40 arrival at Chicago Union Station. Presumably train #28 arrived nearly as early.
BNSF and CP generally seem to treat Amtrak well.
Checking the recent data on amtrak.com for #8 at CHI, by arrival date (origin is two days earlier):
6 Dec, 63 min late
5 Dec, 82 min late
4 Dec, 16 min early
3 Dec, 10 min early
2 Dec, 78 min late (perhaps due to blizards out west?)
Only the previous 5 days of origins (thus the three most recent arrivals) are available on the web. I will try to update this throughout the week leading up to 10 December.