Comment by bananaboy

I have written many old school plasmas and that does look pretty good to me. Here's one I wrote that looks quite similar https://youtu.be/oX-cepvvQds?t=50 You don't do it once per row or column, and you don't call sine/cosine at all except at init time. You generate lookup tables for cosine, and for each pixel of a (typically mode 13h VGA) 320x200 screen you step through the tables with several counters at different rates and sum the values.

Here's someone else writing one that also uses that technique https://youtu.be/X6BpW2N_Sf0

There is an even more oldschool version which was done on XT/286 class machines which was just palette cycling, which didn't look quite as dynamic.