I'm really puzzled by "JSON is for machines, not for humans" types of comments here. FFS, JSON has whitespaces, that alone should answer who it was made for. And making human-readable formats more human-readable is a good thing. JSON5 is awesome.

If the performance of your module suffers from parsing its inputs, you are doing some Really Terrible Thing with your inputs. And if the nature of the task really requires you to parse data quickly and on a big scale, it would be better to ditch JSON altogether and switch to a binary format like protobuf instead.