Measure Page Load Time and Code Execution Time in PHP

How much time does your page or your code need to run? You can measure it with a few lines of PHP. This helps to find the slow parts of a script before your visitors do.

Measure the time of a piece of code

Take the time before and after the code with microtime(true). The difference is the time in seconds.

<?php
$start = microtime(true);

// The code that you want to measure
usleep(250000);          // wait 0.25 second, as a test

$end = microtime(true);

echo "Execution time: " . round($end - $start, 2) . " seconds";
?>

Output:

Measure the full page load time

PHP already knows when the request started, in $_SERVER["REQUEST_TIME_FLOAT"]. Put this code at the end of your page.

<?php
// At the end of the page
$time = microtime(true) - $_SERVER["REQUEST_TIME_FLOAT"];

echo "Page generated in " . round($time, 4) . " seconds";
?>

This is the time that PHP needed on the server. It does not include the time to download the page in the browser.

Memory usage

<?php
echo "Peak memory: " . round(memory_get_peak_usage() / 1024 / 1024, 2) . " MB";
?>

A reusable timer function

hrtime(true) is more exact than microtime and it does not change when the server clock changes. It returns nanoseconds. This function measures any function that you give.

<?php
function measure(callable $task): float
{
    $start = hrtime(true);
    $task();
    return (hrtime(true) - $start) / 1e9;   // seconds
}

$seconds = measure(function () {
    $sum = 0;
    for ($i = 0; $i < 1000000; $i++) {
        $sum += $i;
    }
});

echo "The loop took " . round($seconds, 4) . " seconds";
?>

Related: PHP Functions and PHP Date and Time.

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