Our memory management approach is still not tuned and optimized. There are quite a few low hanging fruits that should provide great improvements, but we have not yet implemented them - Alessandro of Leaningtech
Seriously, I would like to see a warning put on links to that example to the effect that at present it will make your browser use up to 2½ GB more RAM and will thrash your memory. Because it did render my browser (and to a lesser degree my system) unresponsive for a couple of minutes while things swapped.