[whitequark_]

122 MB of it is Wasm machine code of a MinSizeRel LTO build of LLVM; it is compressed to 23 MB by Zstandard when your HTTP client supports that. That is about as small as you can get an LLVM/Clang/LLD bundle to be, and I put a lot of effort into making it smaller.

248 MB of it is an OpenBSD sysroot; it is compressed to 45 MB by Zstandard when your HTTP client supports that. I have not used OpenBSD and have no particular insight into what's inside.