On this subject, one program that has pretty impressive interactive
visualisation is the venerable snd
(http://ccrma.stanford.edu/software/snd/). It displays hours of audio
in a flash and allows you pan and zoom the signal without a hitch. It
only plots an envelope of the audio signal at first, and shows more
and more detail as you zoom in.
Jimmy's comment that there's no need to visualize 3 million points if
you can only display 200 000 is even more true for time signals, where
you can typically only display 1000 to 2000 samples (i.e. the number
of horizontal pixels).
Does the new path simplification code use a similar approach to snd?
I've always wanted something like that in matplotlib...