Optimize all the things!
Many sites will use the views block-display, but few of them enable the block-cache. And yet this simple step will usually provide a decent performance boost to those pages with block-displays.
VBCO is focused on automation: it recommends block-cache settings for views' block-displays, and can automatically set the best cache setting for those blocks.
VBCO is tightly-coupled with views: it inspects the handlers/plugins used by a view display to determine the best possible cache setting based on the views configuration. For example, the user-picture field checks
user_access() in its render function, so if the user-picture field is used by a view display, it should be cached per-role; the user's history timestamp filter is based on the current user, so should be cached per-user.