The first one that I knew had pitted was on lap 3, by which point I'd got over a minute advantage and had lapped the six new cars already. I didn't bother finishing the race.
Something must have gone quite badly wrong somewhere, because even my race strategy was set to use dry tyres to begin with. Only had the issue once though, fortunately.
Just had that myself, albeit I started I started on inters and they pitted the end of the first lap. About 10 laps later they started catching up as I was still on inters as the track dried and was about 10 seconds off the pace for a couple laps.