Antenna far field postprocessing

Dear All,

I am modelling VHF/UHF directive antennas in 3D and I am specifically interested in the far field patterns of the antennas.
I notice that the far field postprocessing is extremely time consuming. My impression is that it takes much longer than actually the integration of the model.
The results look reasonable. But any change to the visualization again may take an hour to compute whereas the model without the far field node may take 30 minutes.

Any hints, anybody?

Cheers
Edgar