Why does xmlsitemap_generate_chunk ORDER BY language and loc

Hi,

is there any reason, why xmlsitemap_generate_chunk uses
'ORDER BY' => 'ORDER BY x.language, x.loc'
and not something simple like
'ORDER BY' => 'ORDER BY x.id'
?

Later option would help me being more performant and use existing indexes. But maybe I am missing something?

related: #1003058: MySQL slow queries