The big advantage of the Eytzinger layout actually comes into play when your binary search isn't branch-free. In that case, the CPU will speculate loads reason

The big advantage of the Eytzinger layout actually comes into play when your binary search isn't branch-free. In that case, the CPU will speculate loads reasonably far ahead, and because both choices tend to be in the same cacheline, this prefetch is rarely wasted. In other words, the big win isn't about reducing the number of cacheline fetched, it's about reducing the effective latency of those fetches. That said, using a similar layout with higher fan-out and SIMD ops doesn't benefit from this effect and is probably still better.