Cache

<?php
$cachetime = 3600;
if (isset($headers['If-Modified-Since']) && (strtotime($headers['If-Modified-Since']) > (time()-3600)))
{
// Client's cache IS current, so we just respond '304 Not Modified'.
header('Last-Modified: '.gmdate('D, d M Y H:i:s', (strtotime($headers['If-Modified-Since']))).' GMT', true, 304);
exit();
}
header('Last-Modified: '.gmdate('D, d M Y H:i:s', (time()-$cachetime)).' GMT', true, 200);
ob_start();
?>
[/pre]

Place this at the end.
[pre]
<?php
SendLength();
function SendLength()
{
if(ob_get_length())
{
header("Content-Length: ".ob_get_length());
ob_end_flush();
die;
}
}
?>