Not sure about the current state but not too long ago the unwind information wasn't stored separately from the regular path which meant that they used up valuable instruction cache.
At least on GCC since 3.x, unwind info has been on a separate section. It is not even machine code (dwarf unwind opcodes are run by an interpreter), so it is unlikely to be in the instruction cache.
The unwind info might end up calling destructors or exception handlers, which might or might not be on a separate page. You are probably referring to that.
