Simulink function block using matlabfunction is very slow

So I generated a matlabfunction varible in the workspace since it is a very long 6x6 symbolic matrix and would like to substitue values into the formula, in order to use it in simulink I have a simulink function block whoch calls an extrinsic function in the directory and which calls the matlabfunction. However, it tales a long time to run the simulation, because it takes this long I have never finished the simulation. Usually when I just call the matlabfuncion in the workspace it would ony take around 5 seconds to give me the answer so I am not sure why it became this slow when it comes to simulink, anyone has an answer?

Thanks in advance