I have included the Gallery Index [using the printAlbumMenu('jump') function] in the HEADER, and want to streamline page loading. What can I do to make the gallery index [printAlbumMenu ('jump')] only load once per session, rather than every time a page refreshes, or new page loads? Thank you.

If the page reloads or a new one loads naturally everything is loaded. There is no way around, that is how it works. (unless you want to do quite some work with JS and Ajax which has other disadvantages then). The easiest is to use the static_html_cache to lower script execution time.