I had that problem in my buick. I was about to take it to my mechanic to repair, but i thought I would try spraying some silicone all around the frame of the window to see if that would help. It did! All of a sudden the window went up quickly.
I have to say I was really skeptical. Even more so when I picked up my can of white grease. There was barely any in it. The pressure in the can hardly got any grease in the channel. But I was wrong. With a total of 1 inch of grease that actually landed in the channel, the window works great!