Not exactly as fast. Without -Bsymbolic, a global variabile with global symbol visibility gets its own GOT entry, meaning access to your global goes through an indirection table that supports ELF symbol interposition. (Which, IMHO, was a bad idea, but you can't unbreak an egg.) With a data structure like this (or with a conventional "struct globals"), there's one symbol at the ELF level to look up instead of one per variable, so your code might end up doing fewer GOT lookups.

The last paragraph was just arcana though. You should be passing -fvisibility=hidden and explicitly exporting from your DSO only the symbols you might legitimately expect some other DSO to use, obviating the issue.