[WARNING] MultiJson is using the default adapter (ok_json). We recommend loading a different JSON library to improve performance.

[洋洋 宋]

when I run selenium webdriver with ruby code,there is a warning which
is "MultiJson is using the default adapter (ok_json). We recommend
loading a different JSON library to improve performance.".
What can I do to fix this warning.

[Dan Franko]

Use another json library.  Check here for a list of supported libraries. https://github.com/intridea/multi_json  Being a warning though means that you could just ignore it.

[Roger Morton]

>So I commented the warning line out ...of multi_json.rb

That would be one approach. But I would suggest a better approach is to install json gem into your ruby installation.

gem install json

This way you get rid of the warning and get the performance improvements that the warning is talking about.
I tried this and it worked to get rid of the warning. From my understanding this makes the multi_json library have more json adaptor to choose from and so it can "choose the fastest available JSON coder"