Use Views to render precalculated data.

views_render.module

/**
 * Override a view result with nids and render.
 */
function hook_render_view_with_nids($view_name, $display_id, $nids) {
  if (!is_array($nids)) {
    $nids = array($nids);
  }

  $view = views_get_view($view_name);
  $view->set_display($display_id);

  // Create a group with OR operator.
  $view->display_handler->override_option('filter_groups', array('operator' => 'OR', 'groups' => array('1' => 'OR')));

  // Disable pager, header etc.
  $view->display_handler->override_option('pager', array('type' => 'none'));
  $view->display_handler->override_option('header', array());

  // Create filters for that group.
  $filters = array();
  foreach ($nids as $nid) {
    $filters['nid_' . $nid] = array(
      'id' => 'nid_' . $nid,
      'table' => 'node',
      'field' => 'nid',
      'value' => array('value' => $nid),
      'group' => '1',
    );
  }
  $view->display_handler->override_option('filters', $filters);

  return $view->preview();
}