Just to be clear, that "speed-up" is not a good thing: Those 100 years were a lot less deadly in total. The World Wars were even shorter and much deadlier still. A possible next full-blown conflict between major powers will only last hours -- and end civilization.
Well the 30-year war definitely showed technology-driven speed-up. Before the printing press we had wars that lasted for 100 years [0]
[0] https://en.wikipedia.org/wiki/Hundred_Years%27_War