<p>I have a windows c# application and I want to display a pdf file, located on a webserver, in an acrobat com object added to my form. </p>

<pre><code>pdf.loadfile(@"http://somewhere.com/nowwhere.pdf")
</code></pre>

<p>As my pdf is large, the application seems to hang till the entire file is loaded. </p>

<p>I want to read the large file without the user being under the perception that the application is hung.</p>

Three suggestions.
the first would be to break it and load a page at a time like some online books do. This is a bit annoying but would save you the loading time. I think ItextSharp has some functionality to do this.
Second try compression. again itextsharp has tools that allow for this
My third suggestion would be to check out
This thread
. choose a few nerdy loading phrases and use an animated gif to distract your client from the long loading time. Obviously this is a last resort, but could useful.