Question about performance between for iteration and extension function

[Lin Yo-An <cornelius.howl@xxxxxxxxx>]

Hi folks,

I am in doubt of this, I thought pure php iteration is slower than calling
join or other extension functions.

but the result shows:  https://gist.github.com/b2a94c94ca66a55814d4

Using Pure PHP for iteration is faster than using join function. why ?
because of the php runtime typecasting ?

And json_encode is the most slowest.

-- 
Best Regards,

Yo-An Lin