What are the advantages and disadvantages of using cookies versus sessions for tracking image reload times in PHP?

When tracking image reload times in PHP, using cookies allows for persistent tracking across multiple page visits, while sessions only track within a single session. However, cookies can be disabled by users, affecting the accuracy of the tracking data. Sessions are more secure as the data is stored on the server side, but they require additional server resources.

// Using cookies for tracking image reload times
if(!isset($_COOKIE['image_load_time'])) {
    $load_time = microtime(true);
    setcookie('image_load_time', $load_time, time() + 3600); // Cookie expires in 1 hour
} else {
    $previous_load_time = $_COOKIE['image_load_time'];
    $current_load_time = microtime(true);
    $reload_time = $current_load_time - $previous_load_time;
    echo "Image reload time: " . $reload_time . " seconds";
}