Benchmark One - High

1.01460683 - 10000 cycles

Benchmark Two - High

1.02928255 - 10000 cycles

Benchmark One - Low

1.23014476 - 10000 cycles

Benchmark Two - Low

1.21406448 - 10000 cycles

Current Benchmark

<?php 

echo str_replace(
    
'Hi',
    
'Hello',
    
str_replace(
        
'u',
        
'you',
        
str_replace(
            
'r',
            
'are',
            
str_replace(
                
'2day',
                
'today',
                
'Hi, Jim, how r u 2day?'
            
)
        )
    )
);

 
?>
vs.
<?php 

echo str_replace(
    array (
        
'Hi',
        
'r',
        
'u',
        
'2day',
    ),
    array (
        
'Hello',
        
'are',
        
'you',
        
'today',
    ),
    
'Hi, Jim, how r u 2day?'
);

 
?>

Conclusion

NOTE: I believe this test to be inconclusive, when taking into account margins of error. Times also fluctuated between the two benchmarks every cycle.

After an average of 10000 cycles, the fastest option is Benchmark 2!

<?php 

echo str_replace(
    array (
        
'Hi',
        
'r',
        
'u',
        
'2day',
    ),
    array (
        
'Hello',
        
'are',
        
'you',
        
'today',
    ),
    
'Hi, Jim, how r u 2day?'
);

 
?>


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