Unintentional connections by TBB to Google and Yahoo servers

The TorBrowser establishes unintentional connections to the following servers:

fusion.google.com/favicon.ico google.com/favicon.ico add.my.yahoo.com/favicon.ico

It remains mysterious to me why those connections do not occur at each start up of TBB, but periodically.

In fact, TBB should not permit connecting automatically to these data miners and loading items into the cache.