all taxonomy queries: instant death

Hi,

On my taxonomy pages it seems this function is executed which almost kill my server hence I have large vocabularies. Any ideas why?

/**
* Build a array of all taxonomy terms.
*/
function _service_links_get_terms() {
$types = array();
$vocabularies = taxonomy_get_vocabularies();
foreach ($vocabularies as $vocabulary) {
$tree = taxonomy_get_tree($vocabulary->vid);
foreach ($tree as $term) {
$types[$term->tid] = $term->name;
}
}

return $types;
}