First clean all the connections. The connections to the motors as well as the switch connections. Make sure the window tracks are clean as well and lube them up. I do believe that rodney dickman sells a window helper that speeds things up a bit. I'm pretty sure others will chime in as well.
Mine were really slow too. I'd even push up or down on the glass while holding the switch to make them move faster. There is a thread about removing the switch, taking them apart and cleaning the contacts. That might work with some cars, but it didn't help mine. There is another thread about installing power window relays (power is routed through the switch on our old cars whereas newer cars use relays). I completely disassembled my doors removing all the tracks and the motors. It is a long job, but when I was done the windows probably move 3-4 times faster than they did previously. It is necessary to drill out several rivets per door (4-5?) and replace them with 1/4" bolts and captive nuts. I used solvent to remove all the old window track grease (it has completely solidified), relubed everything and put it back together. Like I said, it was very time consuming, but well worth the time IMO.
