It throws an error if you try to plot more than 5000 datapoints by default, internally altair produces a JSON representation (vega-lite) that is larger than the

It throws an error if you try to plot more than 5000 datapoints by default, internally altair produces a JSON representation (vega-lite) that is larger than the data you plot (because it contains the data you plot, plus formatting information). If you save this output, for example in an ipython notebook, it gets phat pretty quickly. Altair is still great though, but this issue makes it occasionally annoying.