Scene is being loaded with delay in facebook game which is made in unity

I have made a game in unity3d and I want to upload it as a facebook game (app) on facebook. So I have followed the steps http://forum.unity3d.com/threads/150831-Unity-webplayer-into-Facebook-with-Dropbox and my game just work fine when I directly load game from dropbox. But when I am playing game via facebook it loads first scene and after tapping "play game" button (which is present in my first scene) it start downloading second scene which causes a lot of delay of about 10 minutes. My *.unity3d file size is 49 mb which I have uploaded on Dropbox.Once it has been downloaded it doesn't show any delay after that (second scene load without delay when I press "Play Game" button).

Is there any way to eliminate the delay? Why facebook doesn't download all scenes first time like dropbox does? Please guys help me out.

Thanks in advance.