Here is a possible easy fix for your slow power windows in your Hummer H1 or really any other car too. Do your power windows roll up slow and roll down slow? The fix might be as simple as cleaning and lubricating the window rails. This window was completely stuck even after installing a brand new OEM window regulator. I tried adjusting the front/rear rails with no luck. The fix ended up being simply lubricating the rails!!
Here is what I used to lubricate the window rails:
And here is the link to the brand new OEM Window Regulators for your Hummer H1: