Agreed. I can imagine a situation where GapList might perform better if you were alternating requests to the beginning and ending of the list and GapList happe

Agreed. I can imagine a situation where GapList might perform better if you were alternating requests to the beginning and ending of the list and GapList happened to store them close enough in memory that they were both on the same cache line. But by their names, none of the benchmarks seem likely to test that case.