json is faster.
The only major difference in speed would be parsing time, and that's really dependent on which library and infrastructure you use. My gut feeling is that JSON will be faster to parse, but there are probably more mature XML parsers out there, so it's likely a toss up. If it really matters that much, I'd suggest writing a few performance tests to determine which works faster in your environment.
Some XML formatted responses in favor of JSON are removed. If you plan on using the Streaming API at any point, I'd suggest making the switch to JSON, since XML is not supported there.
For further reference read..
https://www.udemy.com/blog/json-vs-xml/[
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