user2583: I want to render just 10 seconds of my 1920x1080 movie to create the best quality preview for a demo. But rendering process takes the same time as rendering the entire movie (35 minutes). 
Why is it taking so long? 
A guess - is Movie Studio rendering the entire file and then just cropping away the unselected part? How do I render the selection only?
Here is what I do:

select a 10 seconds region in the timeline
go to menu -> Project -> Make movie
pick option Save it to my hard drive
pick format mp4
enable the checkbox "Render loop region only"
click Advanced options and pick Sony AVC/MVC encoder
pick my preset of choice (1440x1080@30p, 1.333 pixel ratio for anamorphic aspect ratio, 25 FPS, 26 Mbps bitrate)
render


user2583: Oh, I found it myself and leaving the answer here in case someone else will get confused by this because the solution is not obvious.
I was setting the checkbox here:

but if I use "Advanced options", Movie Studio ignores this setting!
I have to select it deeper in a hidden dropdown in the "Advanced options" window like this:

And later when rendering the full video, it is important to remember to open that dropdwon again and turn off the region rendering.
Oh, Sony, this is so confusing - two things doing the same, but effective only under specific circumstances.

2583: <p>I want to render just 10 seconds of my 1920x1080 movie to create the best quality preview for a demo. But rendering process takes the same time as rendering the entire movie (35 minutes). </p>

<p>Why is it taking so long? </p>

<p>A guess - is Movie Studio rendering the entire file and then just cropping away the unselected part? How do I render the selection only?</p>

<p>Here is what I do:</p>

<ul>
<li>select a 10 seconds region in the timeline</li>
<li>go to menu -> Project -> Make movie</li>
<li>pick option Save it to my hard drive</li>
<li>pick format mp4</li>
<li><strong>enable the checkbox "Render loop region only"</strong></li>
<li>click Advanced options and pick Sony AVC/MVC encoder</li>
<li>pick my preset of choice (1440x1080@30p, 1.333 pixel ratio for anamorphic aspect ratio, 25 FPS, 26 Mbps bitrate)</li>
<li>render</li>
</ul>
 2583: <p>Oh, I found it myself and leaving the answer here in case someone else will get confused by this because the solution is not obvious.</p>

<p>I was setting the checkbox here:</p>

<p><a href="https://i.stack.imgur.com/gCYJ3.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/gCYJ3.png" alt="Wrong checkbox"></a></p>

<p>but if I use "Advanced options", <strong>Movie Studio ignores this setting!</strong></p>

<p>I have to select it deeper in a hidden dropdown in the "Advanced options" window like this:</p>

<p><a href="https://i.stack.imgur.com/FI022.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/FI022.png" alt="Right checkbox"></a></p>

<p>And later when rendering the full video, it is important to remember to open that dropdwon again and turn off the region rendering.</p>

<p>Oh, Sony, this is so confusing - two things doing the same, but effective only under specific circumstances.</p>
