I've never had a problem with the wiring other than it coming off the back of the switch, and that was solved with the correct retaining nut. If it's just slowness, then it's due to old motors more than anything.
Older chevys also have fairly slow windows, it's how they were new too. The switches are on the help rack if that's your problem. My driveway has had several 200K G bodies, never an issue with the wiring. shrug.gif