Jovan Popovic answers a question I’ve had on my mind:
One of the first questions that people asked once we announced JSON support in SQL Server 2016 was “Would it be slow?” and “How fast you can parse JSON text?”. In this post, I will compare performance of JSON parsing with JSON_VALUE function with the XML and string functions.
The short answer is, JSON parsing should be faster than XML but slower than our historical T-SQL parsing functions.