[StillBored]

None of that is 1/10th as complex as the virt extensions, IOMMU/ATS, etc, etc, etc, Stuff that is common on high end processors these days. If you think x86 is complex, I suggest that you look at aarch64, the smmu, gicv3, etc docs.

Plus, x86-64 basically disables both the things you list. Not that it matters because what is a flat fs/gs/etc register when there is another whole level of page tables for the hypervisor. AKA, you do the translation and store it in a TLB. If you really want to compare this, time how long a modern x86 takes on TLB misses, or for that matter how fast its TLBs are. I think you fill find that they are industry leading...

Same basic thing for the x87, its likely mostly powered down, and when active is probably feeding micro-ops through a SSE functional unit....

So the original posters comment is likely correct, and that has been known for a decade+. X86 if anything has a few accidental advantages, and the idea that its somehow "worse" than the alternatives are provably wrong.