Right but you aren't performance bound by the language - rewriting the brute force for day 14 part 2 in C won't get you anywhere. I think that Eric tries to design the puzzles and the inputs in a way that

- a well implemented smart solution runs in a reasonable time even in a slow language on a slow computer (this is what I meant by not being performance bound)

- some of the exponential growth puzzles can't be realistically brute-forced even with a fast machine and a performant language (like the example you mentioned)