I think the cause of the first AI winter had more to do with some of the early researchers suggesting they'd have solutions to problems within a few months to years that are just now becoming tractable. In retrospect it doesn't seem like they could've gone much faster than they did. New ideas mattered but increased computing speeds probably mattered more. It's not like we would have been able to get dramatically better results than those researchers did by taking what we know now and running it on the same hardware they had back then.