[manwe150]

Both are O(1) datastructures, but indexing a ring buffer is slightly more costly compared to this and insertion is slightly more costly for this than a ring. Probably usually works out in favor of this design though for net performance usually?

[ufo]

I'd love to see performance numbers for this, if they're available. My hunch is that indexing cost would be about the same.

[manwe150]

They both have an offset, but ring buffers aren’t contiguous so they also need a branch or modulus to handle wrap around. Either can be cheap, but clearly that is strictly more costly than not having the extra operation (even if very little). Only matters for random indexing also, since for mutation the situation is swapped

[ufo]

There are many situations where those little differences completely vanish because of instruction pipelining. Only way to know is to actually measure it.