Jovan Popovic points out the performance difference in using the WITH clause in an OPENJSON query:
Here are results of the queries:
SQL Server Execution Times: CPU time = 656 ms, elapsed time = 651 ms. SQL Server Execution Times: CPU time = 204 ms, elapsed time = 197 ms.As you can see, WITH clause specify that OPENJSON should immediately return properties from the JSON array without second parsing. Performance of the queries might be increased 3 times if you avoid double parsing.
That’s a pretty big difference when you specify the relevant data model elements.