Window lifter different fast

Hello dear community. I came across this nice forum via Google and hope you can help me. On Friday I bought an Audi TT Roadster 180 Ps of year 11/2001 with 24,000 km with a really nice equipment like Xenon, Bose, leather, seat heating, electric cover and and and and and. Because the car is not yet mounted, I sat in Friday evening about 1 hour and Saturday 2 hours. But when I took down both window lifters, I noticed that that went from passenger windows much slower about one to two seconds. What could it be, and what costs come to me? Or does this have only something to do with the fact that maybe the battery has hit a little bit, because I have heard the 3 hours quiet cd and had standlight on. I am grateful about every tip. Kind regards Tobias