Extremely slow mex compilation with Matlab 2017a Coder

I have the following situation:

In a huge Simulink model I have self-created interpolation functions with varios dimensions, each occuring several times in the model. In an earlier Matlab version (2010a) I used therefore right mouse click / Real-Time Workshop / Generate S-Function to accelerate the simulation and to save model size. When doing so I have never encountered problems with the duration of this mex-compilation, almost independently of the dimension of the interpolation function - no matter if it was 3-, 4-, 5-, or 6-dimensional.______BUT______ When using today's Matlab 2017a, so right mouse click / C,C++ Code / Generate S-Function I notice an enormous duration dependency during the mex-compilation of the function dimension:

wheras my 3-dimensional interpolation function needs about 10 seconds to produce the associated mex-file,

my 4-dimensional interpolation function needs about 2 minutes to produce the associated mex-file,

my 5-dimensional interpolation function needs about 30 minutes to produce the associated mex-file,

and my 6-dimensional interpolation function didn't produce any mex-file after 19 hours!!!

Am I doing wrong here? Could it be that the earlier Matlab version didn't occupy so much RAM so that the mex compilation was independent of the function dimension? By the way, I tried both Matlab versions also on a different computer, even on a different operating system (Win and Mac), and came to the same conclusion as mentioned above... Any idea would be great! THX!