The file itself is not inserted into the page. This only
affects the environment in which the page is parsed. The benefit is
that the package file needs only be parsed once, and the compiled
versions of the user defined tags can then be used, thus saving time.
It is also a fairly good way of creating templates for your website.
Just define your own tags for constructions that appears frequently
and save both space and time. Since the tag definitions are cached
in memory, make sure that the file is not dependent on anything dynamic,
such as form variables or client settings, at the compile time. Also
note that the use tag only lets you define variables in the form
and var scope in advance. Variables with the same name will be
overwritten when the use tag is parsed.