Upgrading from "Mac OS" 10.11 to "macOS" 10.12 didn't bring a lot of visible changes, but it did bring an interface change.
My mouse's scrollwheel seemed to not work right. Slow movements were ignored, and quicker movements caused web pages to jump too fast.
I did a Google search and found out that I wasn't alone. macOS Sierra changed how scroll wheels function. Why? I don't know.
"USB Overdrive" was a recommended fix. However, after using it for a few days, I started having more and more problems with other things. Drag and drop would sometimes stop working, middle-clicking would stop working, and VMware Fusion would crash even more than usual. In all cases, disabling USB Overdrive cleared the issue up. I've tried contacting the developer about this, but have received no response, and they continue to have the "works with 10.12" blurb on their website.
I found that the Chromium Wheel Smooth Scroller extension for Chrome improved scrolling a lot. Slight movements are no longer ignored.
I currently have its top four settings set to 20, 0, 1, 1.