Also, it's hard to beat gnuplot's speed refreshing a live scatter plot with many thousands of points using the x11 terminal.
And I usually keep computation and plotting separate. Computation produces data files, and a gnuplot script generates plots. This separation of computation and plotting allows updating charts later if needed, collected data can be reused in other plots, and additional data analysis can be performed and charts can be augmented.
So I personally don't see many advantages from integrating chart generation into computational pipeline itself (except for computation monitoring or maybe when user response is needed to direct computation). Because of that, libraries that encourage charts generation from a computed array instead of dumping that data into persisted files feels like an anti-pattern to me.