That's the route I've taken a number of times. Can't speak to where there's construction since last time, though. That's always a wild card.
(Last time I went to Nova Scotia I took that route and did some research along the way!
http://ecomodder.com/forum/showthrea...2-a-21152.html )
If you're passing through on a weekday, I would aim to avoid 6-9 AM local or 3-6 PM (ish).
Also, if you're not pressed for time, I would
HIGHLY recommend getting off the #20, and heading up to the "old highway" #132 that runs along the south shore of the St Lawrence River east of Trois Rivieres. It's a wonderful scenic route: river views, through the old towns, local architecture & old buildings that tickle the eyeballs, nice relaxed pace. Even if you don't want to drive the entire distance on that old route to #85, do at least some of it.