Display algorithm in Fragment Shader
I am new in OpenGL, recently, I am using OpenGL ES to process real time video frame(frame size if about 800 * 600, target GPU is PowerVR SGX543/266 MHz). In this project, we anlyse data of pixel cluster and display the pixel with an algorithm (for example, make a Gaussian Blur algorithm). In my design, the algorithm is implemented in the Fragment Shader（Time Complexity is O(n*n)）, it works, but the frame rate is too low, The normal frame rate is about 60 fpt, when enable the algorithm, frame rate become to 2 fpt.
My question is: "algorithm implemented in the Fragment Shader", is this pattern correct? It seems absolute to fall down the frame rate.