<?php
$time_start = microtime(true);
$c = $modx->newQuery('modResource');
$c->select(array('id','pagetitle','longtitle','content'));
$c->where(array('id:>=' => 6));

$c->limit(10);

if($c->prepare() && $c->stmt->execute()) {
    $collection = $c->stmt->fetchAll(PDO::FETCH_ASSOC);
}

function makePlaceholders($arr = array()) {
    $tmp = array();
    foreach ($arr as $k => $v) {
        $tmp['pl'][$k] = '[[+'.$k.']]';
        $tmp['vl'][$k] = $v;
    }
    return $tmp;
}

$output = '';
$i=0;
$chunk = $modx->getObject('modChunk',array('name' => 'tpl'));
$chunk = $chunk->getContent();

foreach ($collection as $res) {
    $arr = makePlaceholders($res);
    $output .= str_replace($arr['pl'],$arr['vl'],$chunk);
    $i++;
}

$time_end = microtime(true);
$time = $time_end - $time_start;
echo 'Ресурсов: ' . $i . '<br />';
echo 'Памяти скушано: ' . round(memory_get_peak_usage(true)/(1024*1024),2) . 'Мб<br />';
echo 'Время работы сниппета ' . $time . ' сек <br />';

$output = preg_replace('/\[\[(.*?)\]\]/', '', $output);

return $output;