That sounds like what I've been doing to solve a similar problem when I wanted to compute influences (in a 2D environment, with influences radiating out in a given radius from a given pixel, and finding the strongest for any given point). I've achieved a 500x speedup using gpgpu solutions compared to solving it in a purely CPU based way.

Of course, it took longer to write and it needs capable hardware (vertex and fragment shaders are used), but it's fast.