Cost of building a list from string
<p>I need to manipulate a string in python, for this I'm creating a list of characters from the string, since python strings are immutable :</p>

<pre><code>str = 'abc'
list(str)
</code></pre>

<p>The problem is that the string can contain upto a million characters and I am not sure whether creating a list is slowing the code down or not.</p>

<p>What is the complexity of the above task? and is there any better alternative to manipulating strings?</p>
