Compile time or runtime? Compile time reflection would be completely painless and bloat-free.
Having implemented reflection in languages like C(++), before, it is most certainly not bloat-free. There are sorts of 'obvious' things programmers do (like enum-reflection) that end up injecting strings all over the place. The overhead is (worst case) proportional to the source-code size, in those cases. In other cases, you end up with bloat proportional to heavily-utilized template libraries. However, unless the reflection system is very clever, i.e., exposes enough information to the linker to strip duplicate-ish symbols, you end up with a bunch of reflection copies.