Lack of Urgency in LMoP

My group is going through lost mines, and they've finally located Cragmaw Castle, but they've had 3 weeks worth of delays (2 from a near tpk and 1 because they want to rest in town for a week).

I'm trying to think how the villains in the campaign would have made progress without interference during this time and alter the story to reflect that. Maybe have Gundren be dead in Cragmaw after he finally gave up intel and have the BBEG partially succeed in his plot.