Aylin,
Thank you for replying to my post. To answer your question I have tried a few different PDF documents (some I have created some are just from user manuals) and my findings are that larger files, pages of 50+, is when you start to notice a substantial increase in PDF loading times. I will be sending two test PDF documents that I am generating using that 3rd party tool I mentioned in my original post to you on the support ticket. The one is only 2 pages and loads almost instantly, the other is 124 pages and you can see that it takes longer than 5 minutes on average to load. However when opening the PDF normally by double clicking on it outside of using the RadPdfViewer, the PDF shows almost as fast as the 2 page document one. Also I clicked on that link provided in your answer and it seems that the thread is still unanswered.
Again, thank you for your reply and I look forward to hearing back from you