Could you please update us with the version of Android along with the Reader version you have installed ?
Thank you for your reply,
Android version is 4.4.2; Reader version is 15.3.1/133273.
The book is 20MB, not a big one; but it has more than 6000 pages, this maybe the cause of slow renderring speed;
If this problem could be solved, more user will chose to use Adobe Acrobat Reader