Slow when zooming / panning on a canvas with lots of text

[josephernest]

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I add 1000 elements of text on a big canvas with KineticJS, which supports :

panning (north/south/west/east) [with click + drag]
zooming [with mousewheel]

Demo here : http://s419743653.onlinehome.fr/things/kinetic_zooming.html

It works, but it is very slow when we scroll, at least on Firefox (I have a laptop with no real GPU) (but not on Chrome).

How to speed up the rendering (when we scroll or zoom) ? What kind of optimization should be done?