A possible explanation for the difference is that the Dijkstra impl being tested is doing multiple heap allocations at every step, which doesn't seem like a fai

A possible explanation for the difference is that the Dijkstra impl being tested is doing multiple heap allocations at every step, which doesn't seem like a fair comparison. Secondarily I believe in the case of the "opt" version, the compiler might be optimising out the entire algorithm because it has no observable side-effects.