Many of the performance rules in this book deal with how external
components are managed, such as serving them via a CDN (Rule 2), making
sure they have a far future
header (Rule 3), and compressing their contents (Rule 4). However, before
these considerations arise, you should ask a more basic question: should
itself? As we’ll see, using external files is generally better.
Inline vs. External
In Raw Terms, Inline Is Faster