Doubt that combo keeps you focused... peanut butter is so heavy it can slow you down. Apples have sugar that still causes a crash. Crackers are just processed flour... not much staying power. Seen folks crash hard on similar snacks. You need something that digests slower for real steady energy. Maybe try less fat or add some real protein.
So is the fat in peanut butter really enough to slow you down, or is that just a guess? Have you actually tried that specific combo during a long shift?