One character. One friggin’ “J”. 8 hours. I hope no one is keeping track of “lines of code per hour”.
Sounds like he / you acquired some essential domain knowledge in those eight hours. Your code is more efficient, and you understand the problem space. That is what programming is about, not how many lines of code you write.
(When working on a large existing code-base, my goal is to remove lines of code from the project. Writing code means you are writing bugs. Removing code means you are removing bugs :)