Chosen Solution

It’s okay when I adjust one video (Motion app). However, after I add another the one, it starts pausing and slowing down. I can’t move my computer mouse.

Motion 5, Adobe After Effects and Photoshop are very processor-intensive applications that also use a lot of RAM. Opening one of these apps will likely use up a big portion of your memory, let alone opening two. The lag that you’re experiencing is probably the laptop having to reallocate its memory. If you’re going to do heavy video editing and motion graphics on a MacBook Air, then it’s best for you to keep only one of these applications open at a time.