PHP Exceptions vs Error classes

<?php

class MyException extends Exception{}
class MyException2 extends Exception{}

class BusinessLogicError{}
class Error1 extends BusinessLogicError{}
class Error2 extends BusinessLogicError{}

echo microtime(true) . '<br />';
//7.64
$i = 1;
foreach(range(1, 1000000) as $k){
    try{
        throw new MyException2();
    }
    catch(MyException $e){
        $i++;
    }
    catch(MyException2 $e){
        $i++;
    }
}

echo microtime(true) . '<br />';

//1.88 sec
$i = 0;
foreach(range(1, 1000000) as $k){
    $result = new Error2;

    if($result === true){
        //ok
    }
    else{
        if($result instanceof Error1){
            $i++;
        }
        elseif($result instanceof Error2){
            $i++;
        }
    }
}

echo microtime(true) . '<br />';

/**
1280303418.82
1280303426.49
1280303429.49
*/