 distinction might not seem useful now, but they have their own respective trade-offs when it comes to speed and interactivity. Generally speaking, non-statistical layers will be faster and more responsive at run-time (since they require less computational work), whereas the statistical layers allow for more flexibility when it comes to client-side interactivity, as covered in Chapter <a href="client-side-linking.html#client-side-linking">16</a>. Practically speaking, the difference in performance is often 