Theora is VP3 with some more leeway in the hope that the encoder can use the additional parameter freedom to produce better video (which never really happened;

Theora is VP3 with some more leeway in the hope that the encoder can use the additional parameter freedom to produce better video (which never really happened; most of the 1.1 branch was, as I understand it, just cleaning up a lot of old mistakes around e.g. rate control). It's pretty clear that VP8 outperforms it.