Luthier said:

...However this pixel-by-pixel frame analysis and modification takes up additional resources, it in fact delays the showing of each new frame until each pixel of it checked, and therefore the filter is causing deteriorated performance that is especially notable on lower-end machines.

We are continuing to work to optimize the game and to increase its framerate...

So, have a little patience.

Unfortunately this wouldn't help. In order to do a quick average on the contrast values for each square you'd have to access the properties of each pixel in the square anyway. You just can't refer to a single property for a 1 inch square.