Summary

5 concentric waves on a pond same as this:
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Amplitude and phase set using paramaters after line written CYMATICS
50x50 res STL took 20 minutes,
140x140 resolution STL render took 4 hours on a premium 2012 CPU using 24gb RAM.

Perhaps K3D surf can do much higher res maps a lot faster, this kind of resolution MC file has a typical processing time of 1 minute not 4 hours, except that scad is boolean.