This is dirt simple native C++ code compiled with -m32, with structs and pointers (which happens to be generated, but that doesn't matter here)
I would expect that dereferencing a 32-bit pointer on x86-64 has zero overhead compared to dereferencing a 64-bit pointer (though I didn't test it). The only way I can see it being slower in the context of a real program is if the base address is an operand that has to be loaded from memory. But it shouldn't be because it's a 32-bit address space and it should be handled by the VMM, i.e. the base address is constant for the entire process.
I would expect that dereferencing a 32-bit pointer on x86-64 has zero overhead compared to dereferencing a 64-bit pointer (though I didn't test it). The only way I can see it being slower in the context of a real program is if the base address is an operand that has to be loaded from memory. But it shouldn't be because it's a 32-bit address space and it should be handled by the VMM, i.e. the base address is constant for the entire process.