Hmm following construction should be faster:
First of all reverse $b_links
:
$b_links_reversed = array();
foreach($b_link => $b) {
$b_links_reversed[$b->uri] = true;
}
Access to associative array should be faster. And now we can do it with one foreach:
foreach ($google['analytics'] as $index=>$a_link){
if (isset($b_link_reversed[$a_link[0]])){
unset($google['analytics'][$index]);
}
}