I found the chart render performance degraded significantly if its data series’ time stamp vary much. I created a repro example at http://jsfiddle.net/wFC5S/3/
Though there are very few data points in the chart, you can see if I mouse over the chart the tooltip renders very slow. It seems the chart is busy doing mouse event detection and updating tooltip.
I have a use scenario that requires to display data series with very different time stamp in the same chart. It would be great if you can resolve this bug or let me know if there is any workaround (I do need the tooltip).