As the author of org.conman.cbor, I'd be interested in seeing the test data. The only bit that's in C is the low-level bit packing of CBOR values. I might have to revisit the use of LPEG to validate the UTF-8 strings (used because Lua 5.1/5.2 do not have UTF-8 support routines). This also supports references, which are nice (they can allow one to encode a Lua table like "x = {} x[1] = x" (a self-referential table)) that might slow things down as well

Also included in the package is a striped down version of my CBOR encoder that doesn't support the CBOR tagging that's about 1/3 the size, so I wonder how that compares against lua_cbor.