Description:
------------
Not very important, I'm dropping this findings here so they don't get lost in the meanders of web.

These operations (and similar ones) don't require a copy to be performed as the result is identical to the original.

Test script:
---------------
$foo = str_repeat('foo', 100000);
var_dump(memory_get_usage());
$baz = '' . $foo; // $baz is identical to $foo
var_dump(memory_get_usage());

unset($foo, $baz); echo "\n";

$foo = array_fill(0, 1000, 'foo');
var_dump(memory_get_usage());
$baz = array_merge($foo, []); // $baz is identical to $foo
var_dump(memory_get_usage());

unset($foo, $baz); echo "\n";

$foo = array_fill(0, 1000, 'foo');
var_dump(memory_get_usage());
$baz = array_slice($foo, 0); // $baz is identical to $foo
var_dump(memory_get_usage());

// etc...