it was (a little bit) faster. But i'm also not 100% sure it's faster because we saving one if() statement, or because copying the $iv by value 2 times is slower then using a $iv reference, or both.... 

But consider this speedtest:
```php
mt_srand(1);//fixed
define('CRYPT_RIJNDAEL_MODE',CRYPT_RIJNDAEL_MODE_INTERNAL);
$cipher = new Crypt_Rijndael(CRYPT_RIJNDAEL_MODE_CFB);
$cipher->enableContinuousBuffer();

for($j=0;$j<3;$j++)
	{
		$s=microtime(true);
		for($i=0;$i<100000;$i++)
			{
				$cipher->encrypt(str_repeat('a',mt_rand(1,32)));
			}
		echo 'Time: '.round(microtime(true)-$s,3);
		echo "\n";
	}
```

Result with the current code using $iv and $pos as reference:
Time: 15.503
Time: 15.403
Time: 15.442

And the result with the same code using $iv and $pos the previous way:
Time: 15.66
Time: 15.623
Time: 15.607


Here the code using $iv and $pos the previous way:
```php
case CRYPT_RIJNDAEL_MODE_CFB:
    $iv = $this->decryptIV;
    $pos = $this->continuousBuffer === true ? $buffer['pos'] : 0;
    $len = strlen($ciphertext);
    $i = 0;
    if ($pos) {
        $orig_pos = $pos;
        $max = $block_size - $pos;
        if ($len >= $max) {
            $i = $max;
            $len-= $max;
            $pos = 0;
        } else {
            $i = $len;
            $pos+= $len;
            $len = 0;
        }
        // ie. $i = min($max, $len), $len-= $i, $pos+= $i, $pos%= $blocksize
        $plaintext = substr($iv, $orig_pos) ^ $ciphertext;
        $iv = substr_replace($iv, substr($ciphertext, 0, $i), $orig_pos, $i);
    }
    while ($len >= $block_size) {
        $iv = $this->_encryptBlock($iv);
        $cb = substr($ciphertext, $i, $block_size);
        $plaintext.= $iv ^ $cb;
        $iv = $cb;
        $len-= $block_size;
        $i+= $block_size;
    }
    if ($len) {
        $iv = $this->_encryptBlock($iv);
        $plaintext.= $iv ^ substr($ciphertext, $i);
        $iv = substr_replace($iv, substr($ciphertext, $i), 0, $len);
        $pos = $len;
    }
    if ($this->continuousBuffer) {
        $this->decryptIV = $iv;
        $buffer['pos'] = $pos;
    }
    break;

```
(php5.4.9 on linux)