I've noticed the same problem as well when it got colder in my area, the driver's side was a little slower but the passenger side was slow as molasses, I wondered if the rainguards I had installed were causing the problem but when it heated up later in the day they ran fine, I figured with 90k the regulators are likely on their way out at any point in the future and I just avoid opening the windows unnecessarily, besides it keeps the heat in when it's cold outside