/**
 * Implements hook_taxonomy_term_load().
 */
function {{ machine_name }}_taxonomy_term_load($terms) {
  $result = db_select('mytable', 'm')
    ->fields('m', array('tid', 'foo'))
    ->condition('m.tid', array_keys($terms), 'IN')
    ->execute();
  foreach ($result as $record) {
    $terms[$record->tid]->foo = $record->foo;
  }
}