Maybe they chose Flash for performance? Google uses annotated timeline primarily for their Finance site, which has a lot of data. Long time ago, before new JS

Maybe they chose Flash for performance? Google uses annotated timeline primarily for their Finance site, which has a lot of data. Long time ago, before new JS engines (FF 3.1B2, Webkit Nightly), canvas performance was not very good. I remember I abandoned my JS charting experiments because of this. For simple static graphs it was ok, but changing complex graphs based on user input was painful, redraw was not fast enough to have a smooth experience. It was especially bad on Explorer, which doesn't have native canvas support, so it must be emulated (usually using VML via ExplorerCanvas from Google [1]). I think Flot also uses ExplorerCanvas. BTW There are a pure JavaScript solutions for annotated timelines, though they look different - MIT Simile project's Timeline [2] and Timeplot [3]. [1] http://code.google.com/p/explorercanvas/ http://code.google.com/p/explorercanvas/ [2] http://simile.mit.edu/timeline/ http://simile.mit.edu/timeline/ [3] http://simile.mit.edu/timeplot/ http://simile.mit.edu/timeplot/