php - preg_replace VS str_replace (Which one is faster?)

one text

I 'm here after several tests for comparing speed of preg_replace & str_replace. Some documents claim that str_replace is 2x faster (because its simpler structure) but in my tests, each time preg_replace was faster a little!

The conditions :

PHP 8.1 & 7.2
Size of array : 8 millions rows

The average result :

preg_replace :  11.03159403801 s
str_replace  :  11.209521055222 s

And This is my sample code :

<?php

    //open file
    $uri = 'src.csv';

    //read csv
    $content=file_get_contents($uri);
    $lines = explode(PHP_EOL, $content);
    
    //set timer
    $start = microtime(true);
    
    foreach ($lines as $line) {
        
        //$array [] = run_preg_replace ($line);
        $array [] = run_str_replace ($line);
        
    }
        
    
    //calc time
    $end = microtime(true) - $start;
    
    var_dump($end);
    var_dump(count($array));
    
    
    function run_preg_replace($str) { // remove new line and spaces
        
        return trim(preg_replace('/\s+/', ' ', $str));
    }
    
    function run_str_replace($str) { // remove new lines
        
        // Create an array with the values you want to replace
        $searches = array("\r", "\n", "\r\n");
        
        return trim(str_replace($searches,' ',$str));
        
    }
    
?>

So it is a rumor or my code isn't good enough for this comparision?