Eve-VP9

Eve-VP9 is a proprietary VP9 video encoder developed by Two Orioles, LLC, an organization primarily known for their work on dav1d, the most widely used AV1 software decoder.

According to the Two Orioles webpage on Eve-VP9:

At top quality, EVE-VP9 provides nearly 20% better compression than libvpx at the same speed; 10% better compression than x265 at 50% faster speed; and compared to x264, EVE-VP9 is nearly 40% better.

Sparse visual comparisons and dated numbers are provided by the company, but no further details are available.