Der fertige Brei

[Raketenhandbuchvorleser]

<?php
if (! isset( $_GET['URL'] ) ) {
  $_GET['URL'] = 'https://www.example.com/';
}

$options = 'time_namelookup:%{time_namelookup}\n'
         . 'time_pretransfer:%{time_pretransfer}\n'
         . 'time_redirect:%{time_redirect}\n'
         . 'time_total:%{time_total}';
         
$sys = 'LANG=C curl -I --write-out "'
       . $options . '" '
       . escapeshellarg( trim ( $_GET['URL'] ) )
       . ' 2> /dev/null | grep -P \'^time_\';'
     ;

$ret = `$sys`;

$ar = explode( "\n", $ret );
$erg = [];
foreach ( $ar as $row ) {
	$row = trim($row);
	if ( $row ) {
		list( $name, $value ) = explode( ':', $row, 2);
		$erg[$name] = $value;
	}
}

print_r( $erg );

Array
(
    [time_namelookup] => 0.004270
    [time_pretransfer] => 0.458685
    [time_redirect] => 0.000000
    [time_total] => 0.604829
)