The idea is, suppose I did a trisect, splitting the range [start,end) into [start,A), [A,B), and [B,end). At each step, I test commits A and B in parallel. If b

The idea is, suppose I did a trisect, splitting the range [start,end) into [start,A), [A,B), and [B,end). At each step, I test commits A and B in parallel. If both A and B are bad, I continue with [start,A). If A is good and B is bad, I continue with [A,B). If both A and B are good, I continue with [B,end). This lets me rule out two thirds of the commits, in the same time that an ordinary bisect would have ruled out half. (I'm assuming that the tests don't benefit from having additional cores available.) In general, for an n-sect, you'd test n - 1 commits in parallel, and divide the number of remaining commits by n each time.