string vs string_view

it -> 1

Function	Milliseconds	Microseconds
substring	1867	1867451
substring_view	13	13608
substring_view_const	9	9614

it -> 2

Function	Milliseconds	Microseconds
substring	1746	1746522
substring_view	12	12727
substring_view_const	9	9970

it -> 3

Function	Milliseconds	Microseconds
substring	1795	1795858
substring_view	11	11767
substring_view_const	8	8827