Toilet flapper closes too slowly
#1

I have spent a few hours over the past week trying to fix a toilet problem at my girlfriends house. When the toilet flushes, the flapper stays up a good 15 seconds or so. The Tank starts filling within a couple of seconds after the handle is pulled. It seems like the flapper should close sooner, compared to toilets in my house. In the bowl itself there is a "whirlpool action" going on when we flush. I have replaced all the "guts" inside the tank. Any ideas?