For the past 2 or 3 versions of Fusion I've noticed this. When entering a toolpath simulation (or while the simulation is paused) there's only a slight delay (more than I've experienced in 3/4 years using Fusion). However, once the simulation starts playing there is a pretty big delay between the trackpad gestures I use and what happens on the screen.
I have only experienced this behavior for the past 2 or 3 updates of Fusion.
For example:
