The intro of this article repeats the common assertion that

> ARM is the most relaxed, allowing significant hardware optimizations; and x86 is the most strict, enforcing a very strong coherency model that doesn’t allow a lot of room for optimization

but I've seen some compelling arguments that a relaxed model doesn't necessarily have much of a benefit, https://fgiesen.wordpress.com/2026/08/25/memory-ordering-in-...