title: How to manage picture previews correctly
body: <p>I'm developing a C# software that is able to show previews for files. Basically, there is a  tree at the left that shows the disk filesystem entries, and a panel on the right that will show a preview of files selected in the tree, in a resizable panel that contains a docked <code>PictureBox</code>. Initially I only show preview for image files.</p>
  
  <p>This software is designed for game developers, so I need to support all the image formats, I will use the great <a href="http://www.imagemagick.org/script/index.php" rel="nofollow noreferrer">ImageMagick</a> library for this purpose. The key is that some image files could be big, very big so, I have several questions, about performance and memory consumption.</p>
  
  <ol>
  <li>Do I need to thread the load of the picture? Always, or only if the picture is very big?</li>
  <li>Would be a correct if I load the picture directly in the <code>Picturebox</code>, or should I calculate a smaller size image (like a thumbnail or something similar), save it to disk, and then, show it?</li>
  <li>Someone knows where can I download big picture files to test my preview with really very large files.</li>
  </ol>