Mouse acceleration is a feature that speeds up or slows down the mouse pointer in relation to how fast you physically move the mouse. On Windows, I’ve had this feature turned off for years, because it’s annoying while playing games. On macOS though, you can’t turn it off unless you set tracking speed to 0, which isn’t ideal. Edit 2023-09-21: macOS 14 Sonoma allows you to turn this off from the mouse settings pane.
I stumbled upon the open source LinearMouse, which can disable acceleration while keeping tracking speed the same. Now my pointer is motoring around the screen the way I’m used to! No more annoying slowdowns when I’m nearing the end of my range of motion. Feels much more responsive.
I don’t recommend turning it off for the trackpad though, the acceleration is helpful there. On my MX Master 3 it makes a big difference.