Use single quoted strings unless you need to interpolate variables into your string. This saves PHP the time to scan the string for contained variables and saves about 50% execution time. here is a benchmark:

benchmark:
<?php

function getmicrotime($t) {  

       list($usec, $sec) = explode(" ",$t);  

       return ((float)$usec + (float)$sec);  

}  

 

$start = microtime(); 

$a = array(); 

for($i=0;$i<100;$i++) { 

     array_push($a, "Aaron rules!"); 

} 



$end = microtime(); 

$t1 = (getmicrotime($end) - getmicrotime($start)); 

echo "<pre>double quotes: $t1<br>"; 

 

unset($a); 

 

$start = microtime(); 

$b = array(); 

for($i=0;$i<100;$i++) { 

     array_push($b, 'Aaron rules!'); 

} 

$end = microtime(); 

$t2 = (getmicrotime($end) - getmicrotime($start)); 

$t3 = $t1-$t2; 

echo "single quotes: $t2<br>difference...: $t3</pre>";

?>

Results:

double quotes: 0.001505970954895
single quotes .: 0.00078308582305908
difference........: 0.00072288513183594

The trick is from: http://www.webmasterworld.com/forum88/335.htm