gistfile1.php

<?php

$cacheFile = 'cache/cache.html';
$cacheTime = 4 * 60;
// Serve the cached file if it is older than $cacheTime
if (file_exists($cacheFile) && time() - $cacheTime < filemtime($cacheFile)) {
    include($cacheFile);
    exit;
}
// Start the output buffer
ob_start();

// put your shit here

// Cache the contents to a file
$cached = fopen($cacheFile, 'w');
fwrite($cached, ob_get_contents());
fclose($cached);
ob_end_flush(); // Send the output to the browser

?>