Simulink runs slower on Matlab 2017b

I am running the "Exact Same Simulink Model" on Matlab 2013b & 2017B . However, the performance on thses two versions are very different.

On Matlab 2013b, it approximately takes 0.5 ~0.7 seconds to run.

On Matlab 2017b, it takes 5.5 ~ 6.5 seconds to run.

I used "Simulink Profile viewer" & found that on MATLAB 2017b "Link & Compile Phase" consume a lot of time.

It is really surprising to see that "Matlab 2017b" is slower compared to "Matlab 2013b".

I am running the simulation in "Normal Mode" on both of the Matlab versions.

Can any one point out the reason for slow behavior of the simulaiton in Matlab 2017B ??