My buddy did the complete drive to Whistler last month, driving up Friday evening and back Sunday afternoon. He said some areas were bumpy, some areas had pylons, some areas were limited to 50km/hr, and some of the normal passing zones weren't available.

They went camping just past Squamish this month and it was much of the same, leaving Friday day and returning Sunday.

He thinks the impact is tough to judge and pretty dependent on if you get stuck behind slower cars where the passing has been reduced. However, you're also gaining from improvements already completed. His guess is an extra 10-15 mins. However, he went during the weekend. Construction schedules may be reduced during the weekend and increased during the weekdays.

I'm assuming you're referencing these websites which show the construction going on and suggest that in a worst case scenario, you should not be delayed more than 45mins from West Vancouver to Whistler. I'll toss them in the thread for reference.
http://www.gtmconsulting.com/info/pr...elling-sts.htm
http://www.seatoskyimprovements.ca/