I think the slowest is the Kathgodam Shatabdi with an average of just 50 kph closely followed by Dehradun one. Kanpur Shatabdi, I think, is the fastest with average of ~88 kph, faster than even BPL one due to less stop and continuous 130 kph run. That being said, Kanpur one is always LESS packed and MORE cancelled than Lucknow Shatabdi since it is basically a reverse variant of the latter.