Why large arrays are extremely slow to handle?

[nix@xxxxxxxxxxxxxxxx]

Tested on AMD Phenom(tm) II X6 1090T Processor 3.6GHz using one core.

I think there's is a big flaw somewhere that causes the following:

#!/bin/zsh

emulate zsh

TEST=()

for i in {1..10000} ; do

TEST+="$i" # append (push) to an array

done

--- 10K
time ./bench
real    0m3.944s

--- 50K BOOOM! WTF?

time ./bench
real    1m53.321s

Does not make much sense to me. Im also a PHP developer. Just for
comparison, let's do the same with PHP.

<?php

$test = array();

for ($i=1; $i < 50000; $i++) {

$test[] = $i;

}

print_r($test);

?>

--- 10K

time php TEST_PHP
real    0m0.011s

--- 50K

time php TEST_PHP
real    0m0.025s


Any ideas why it's extremely slow? I have need to use very large arrays
(even over one million elements in a single array) but it's currently
impossible due to the above.