Time complexity: Simulink Vs Matlab Code

From the computational complexity point of view, which one is more effiecient Simulink or Matlab code ? I have observed that for the same circuit analysis, Matlab code takes less execution time as compared to Simulink. Even, I solved a simple ODE using ODE1 solver in SImulink as well as using Matlab Code and found that Matlab code is more efficient. Can someone please explain the reason behind this ?

Thanks in advance !