Wall walks may not seem that difficult, until you start doing them one after another in a workout. In order to become more efficient in this movement, I recommend two things:
1. Push-up to your knees before you put your feet up on the wall.
2. Attempt big strides with your hands. Ideally, you can do it in 3-steps.
This short video explains the simple, yet effective, tips in making wall walks effortless and fast.