try other Go json parsers

[Phillipmartin]

ffjson is good, but JSON marshaling is still the single most expensive operation we deal with.

[sroberts]

Any ideas what library you're going for json parsing next?

[Phillipmartin]

ffjson's code generation stuff currently only works for libs, so I want to see about making that work for non-libs, or do a custom JSON serializer for my dnsLog structure.

I also read something about https://github.com/buger/jsonparser recently. seems parsing focused, but maybe it will speed up creation as well.