Bokeh slow in Firerfox, fast in Chrome

I’m rendering a 4000 point spectrum using bokeh.

plot = line(x, y,
plot_width=600, plot_height=300,)
script,div = components(plot, CDN)

then deliver XML(script) into a web2py template.

I’m not using the server, the html template includes these lines:

It works, but is slow in Firefox and IE. In Chrome it is fast.
In Firefox it is 25 seconds to generate the plot, with a similar time in IE.
In Chrome the same operation takes 1 (one) second.

What am I doing wrong?