plot_density slow for large number of particles
In the notebook RingCyclotron.ipynb the plot_density function is very slow for the example. I think it would be much faster and less memory-hungry if a histogram is made instead of scatter plot with colours.
e.g.
plt.hist2d(xdata, ydata, (50, 50), cmap=plt.cm.jet)
gives within a second:
@frey_m : I can add this if you'd agree.