I made a GoLang package which serializes Json from Structs. The package is here. I have an open issue, where I am trying to optimize the library. Find the issue here

I made a GoLang package which serializes Json from Structs. The package is here. I have an open issue, where I am trying to optimize the library. Find the issue here
Good work but
"encoding/json".Marshaldoesn't do the same thing?