PHP timeout in function username_list

Hello,

In wordpress multisite with 15000 users the function username_list in Helpers.php make php timeout.
I replace de script :

return array_reduce($rul_userresults, function ($carry, $item) {

            $carry[$item[0]] = $item[0];

            return $carry;
        });

by :

$out=array();
        foreach($rul_userresults as $i) {
            $out[$i[0]]=$i[0];
        }
        return $out;

and it’s work fine, maybe the array_reduce is to heavy !!!