In older versions, swiping up would cause it to swipe up at full speed. Now, it tries to go the speed you move your fingers at.
I experienced the same thing on my early 2014, i7, 8 GB RAM macbook air. To get mission control to react the same way El Capitan did, I had to give it a serious hard 4-finger flick. It was very uncomfortable, as I rely on fast, smooth app switching through mission control for my workflow. It felt very unnatural. But if I did normal 4-finger swiping, it was too slow and I would run out of room on the trackpad before the windows had completely spread.
I also noticed that there was an issue in Microsoft Word for mac while using Sierra. I have to use word for work and often get files that need constant zooming in/out. So I always hold the CTRL key and 2-finger up/down for quick zooming in/out. On Sierra, the zooming was so jittery, "stuttery", unpredictable and far from smooth. I'd spend way too much time trying to get the right level of zoom, as I'd either go far or not far enough.
Fortunately, I made sure to do a time machine backup right before the sierra installation so I utilized it and rolled my system back to El Capitan. I really hope in a future update, Apple reverts these animations to El Capitan movements. I would love to have Siri on here. I played around with it and it was awesome. It would be a serious help, but an un-interrupted workflow was sadly more important.