Cache array data

Do not ever repeatedly access the same element in an array unless you absolutely have to. Try running the following code on your own machine:

<?php
    $START = time();
    $foo['bar'] = "test";

    for ($i = 0; $i < 10000000; ++$i) {
        if ($foo['bar'] == "test") {
            $j = 0;
        }
    }
    $END = time() - $START;
    print "Array took $END seconds\n";

    $START = time();
    $testvar = $foo['bar'];

    for ($i = 0; $i < 10000000; ++$i) {
        if ($testvar == "test") {
            $j = 0;
        }
    }
    $END = time() - $START;
    print "Var took $END seconds\n";
?>

Running that took 38 seconds for the repeated array access, and 32 seconds for using a variable - the reason for this is that accessing array elements time and time again requires PHP to find the element inside the array, which is comparatively slow.

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