Recommended computer capacity?

Hi, I’m going to join certification training in September and it occurred to me that I might need a new computer for this. I have an 8-year-old MacBook Pro I recently inherited, which has been fine for most things. However, the other day I was working on putting a video together on iMovie for a volunteer group (trying to learn some of the things I might need to do as a self-employed coach, like edit my own videos) and I realized it was too slow for ongoing video editing once I start doing coaching videos/courses.

Do you have recommendations on computer capacity and software used to be able to produce your videos effectively and efficiently? E.g., MacBook Air versus MacBook Pro? Any specs to look for or avoid? Thank you.