Tab icons cause excess memory usage

[rnewman]

1. Open a bunch of .jpg URLs.
2. Open a new blank tab.
3. Relaunch the browser.
4. Observe that about:memory shows all of the cached images as occupying memory, even though the tabs are inactive.
5. Observe that every page's favicon is kept in memory, too.

I'd like a mode where I can disable pre-fetching favicons for inactive tabs, and otherwise disable all the image work that Tab Center does; it's prohibitively expensive for large tab sets.

[zeroibis]

Does it still fetch the screenshot of the page even when set to minimal? It would make sense for it not to even bother to fetch a page image if it is not going to display it anyways.