Slow performance opening PDF files the lag scrolling through pages

Hello, 

Our developers are using your service to display PDF files in a site we are launching. However, from our internal netwotrk opening the files via the PDF-SDK is very slow (30-60 seconds) for a 5Mb file. It can take longer again to scroll through pages once the file is opened. The PDF files are hosted on a external Goolge server. If we use Adobe Reader client app to open the files directly from the web server they open up near instantly. I suspet our Enterprise firewalls and proxies may be blocking access in some fashion. Is there a guide available for optimal browser/network configuration when using this service? Are there any other tips/hints that coudl be shared?

Kind regards,

Stu