Keep the following in mind to improve performance:
Image optimization is key for improving performance. Refer to Optimizing Images in Fixed-Layout Books for methods of optimizing images.
Limit the number of animations per page; keep only those that are most necessary.
Use CSS (not JavaScript) for animations.
Use CSS 3D transforms instead of setting top/bottom/left/right positions. This creates smoother transitions because they are hardware accelerated, but should be reserved for high-priority elements.
Reduce page complexity.
Performance is best when JavaScript is tailored to the book. Third-party JavaScript libraries can often be large and may result in poor performance.