chain calculations slow down sharply as the items became large

hi,all, I have got a problem when run opengles shader on mali-t760 gpu. In the fragment shader i calcuate the color as follow:     vec4 color = (((((Coef5*color+Coef4)*color + Coef3)*color+Coef2)*color + Coef1)*color+Coef)*color; this