Why glibc's fstat() is slow

Why glibc's fstat() is slow

I wonder if people looked at what glibc would use when they were bootstrapping these two arches,

What I don't get is why would they have to think about that code at all when bootstrapping. There is an architecturally neutral implementation of fstat() and friends, and all the person working on the porting should need to do is to connect each system call implementation to the low-level mechanism the particular architecture employs to jump from userland to the kernel.