Fusion requires lots of your computer's resources. Close other software that you don't need.
If Fusion 360 is behaving strangely, or you can't do something you expect to, it is usually because other software is causing a conflict
Too many applications cause conflicts. Close them.
Instead, just Finder, Fusion 360, and maybe one other application are ideal
Create a new folder for your project. This way, all the files you need for your design are in one place. Also, it ensures that Fusion 360 automatically saves your work in the right place. You'll never lose anything by accident.
Use the"Edit Feature" function to change an action you did. Just click on the feature in the timeline, and select "Edit Feature". In the box, change the values. This is more efficient and more accurate than just doing the action again. Also, you reduce the number of steps in your timeline, which makes it easier to understand and improves the performance of your computer.
Build your design "in place". If your design has multiple parts, it's best to build them in place, rather than building them in separate files and joining them later. This way your can always be sure your parts fit. This will save you lots of time.
Use the "Light Bulb" to turn off parts you don't want to see.