iBooks load, scroll, page turning super slow and laggy with highlights

I'm reading a medical textbook on the iPad using iBooks, and the textbook cost me USD$249. It's frustrating when I found that iBooks can't even handle simple tasks like scrolling or page turning well when I have highlights in the book. Hope this can be fixed as soon as possible, I'm currently using the new iPad(3th Gen), and I don't think this thing is too out-dated for handling iBooks, I assumed that this is a software issue.