It sounds like a lack of years of experience in a given specialization. When I graduated university and finished internships, I was fast at coding OOP enterpris

It sounds like a lack of years of experience in a given specialization. When I graduated university and finished internships, I was fast at coding OOP enterprise-type applications and systems-level C programs. Now that I've spent so much of my career doing other things, e.g. reverse engineering and infra work, my coding is less than a quarter as fast. There are also considerations as to how productive you are at working for hours straight, and also whether the "fast" people are creating durable architecture.