On 2.8 and 2.81 the playback of a shape animation or armature deform is very slow if we use the subdivision modifier. In others 3d software but also the Blender 2.79 the speed is really much higher (with heavy models up to 100 times slower).
Slowness increases with detailed models with many vertices.
For realistic face and character animations having fast subdivision helps animators see animations in real time, at 24fps or higher. Opensubdiv allows this in many 3D software.
There was a 2014 video where Sergey showed an animated dragon with active and finally fast subdivisions. Now it seems to be back in 2013.
I think the increased performance of OpenSubDiv is a priority for modeling and animation.