Post deform subsurfing

Lately, I've been having a lot of performance issues with skinned meshes. In the game that I'm currently working on, a character with about 2K polys being deformed seems to cost me a lot of frames. With three characters at that level on screen, I'm dropping to 30fps, which is playable, until you consider the fact that there's nothing else in the map at the time.

One idea that I just got is to subdivide the mesh in after the skinned renderer deforms it, allowing for me to perform solid animations while maintaining quality character models.

I'm not asking anyone to provide me a script for this, I'm simply asking if this is theoretically possible(at least, in the way I describe) and if it'd give me any significant performance increase.