Free accounts are not affected in any way when it comes to execution speed, I believe. Or at least it never seemed to be significant for performance kata, and good solution should pass no mater if submitted by paid user or free user.

I am going to mark the issue as resolved, because I strongly suspect the problem is in your code. If you have some proper evidence that the kata is broken, please come back and reraise the issue with more precise information on what's wrong.