I like that you put performance first, it's often neglected first. I would just try to opt for another programmer splitting the work.
That the plan... initially. They had something come up and couldn't participate (like 1,5 days before jam start). We were initially awaiting a 2D artist to join as the 5th person (5 person team limit) so we didn't really bother looking for another dev... they never joined :). Welp. lesson learned, always have options and people ready beforehand.