JSON serialization of ["Hello world !"]

This benchmark must serialize array ["Hello world !"] fastest as possible.
Goal is to benchmark time taken to serialize it without any added code.

Call GET
Response ["Hello World !"] Example

PHP

#1 PHP 7.0 timer 0.1 ms
38,726
#2 PHP 7.1 timer 0.1 ms
38,205
#3 PHP 7.2 timer 0.1 ms
37,491
#4 PHP 7.3 timer 0.1 ms
37,076
#5 PHP 5.6 timer 0.2 ms
33,794

JSON serializers