Yes it is. Nowhere does the kata mention that the answer must address a particularly high performance constraint. It just says you have to find the earliest gap between primes in a set interval, and my algorithm does just that, and in a few milliseconds, which is hard to beat in the first place. It just doesn't pass because the amount of tests in unreasonably high. Anyone can order millions of tests to pass a kata and thus force valid solutions to timeout. It's just stupid and the only thing it does is create frustration in those who've actually put time and effort in putting together those solutions. Feel free to differ, but from what I've read in the comments, you should at least acknowledge many feel that way.

The description should mention whether the odd characters or the even characters should come first when concatenated instead of leaving people guessing.