I found this interesting repo: https://github.com/Dogwei/Swifter.Json
One thing that caught my attention was this benchmark and I wanted to get some clarity from Demis on this:
ServiceStack.Json, Jil, LitJson, NetJson and etc libraries are not shown because there are too many errors; if necessary, you can clone the test program on GitHub and run. Most of the Json serialization libraries of .NET have been included.
At the end of the day, we are heavily invested in ServiceStack in our solutions and I just want to make sure that in all areas ServiceStack is competitive in performance and memory utilization compared to other libs in the ecosystem.