If you have a favicon.ico
file with its declaration in the HTML code, iOS Safari and Android Chrome won't load it (tested on iPad Mini and Galaxy Nexus).
However, if you have Apple Touch icons, they will be loaded immediately by some browsers, not when the page is bookmarked or added to home screen:
- iOS Safari waits for bookmark or add to home screen events. Good.
- Android Chrome loads
apple-touch-icon-152x152.png
on page load. Arguable.
If network performance is a major issue to you, you should either study the behavior of various devices... or remove all the extra icons.