Comment 2 for bug 1833150

It's not a feature, of course :-), but not quite a bug either. When the type passed to MEM-AREF is not known at compile-time, it has to do a bunch of calculations at runtime. The same applies to virtually every other CFFI function.

We could try to speed up the slow path. For starters, we could run the statistical profiler with you microbenchmark and see if there's any low-hanging fruit. But, it's usually the case that the type is known at compile time.

I'll tentatively mark this issue as "Won't Fix", but perhaps you have a strong use-case that'll motivate us to change this to a Wishlist item. :-) What's your use case?