Low speed problem because of coder.extrinsic

Hi everyone,

In order to change the picture of mask icon (as light illustration) in simulink, I was forced to use "coder.extrinsic" as following:

function showImage(input)
coder.extrinsic('set_param')
ModelECU= 'Project/Light';
if input==200
    set_param(ModelECU,'MaskDisplay','image(imread(''Brake.jpg''))'); 
else    
    set_param(ModelECU,'MaskDisplay','image(imread(''white.png''))'); 
end

There are several other lights and it has reduced the speed of process dramatically. Is there any solution or even any other way to illustrate the lights?

Thank you in advanced.