Bug 125201 – Performance issue (with KineticJS) which goes away when dev console is open

• Status: NEW
• Component: Canvas

[Piers Goodhew]

I've been trying to put together a simple schematic editor using KineticJS (and JSFiddle) which has some fairly severe performance issues when I select 3 objects and try to move them at once. However when I invoke the JS profiler (or any other part of the web inspector it seems), the problems go away.

Steps to repeat:

Open the above URL
Run the code by clicking "run" in the top left
In the canvas area at the bottom-right, select the 3 boxes (using shift, no marquee yet) and try to drag them. Beachball ensues for a time.

This does not occur if you only select 2 boxes, or if you have any part of the web inspector open.

It occurs much less repeatably if you run the code outside JSFiddle (I don't actually have it hosted anywhere).

Also, later versions of the same code, e.g. http://jsfiddle.net/LAgBF/31/ (which has partial marquee select) do not always exhibit the problem.

[Radar WebKit Bug Importer]

<rdar://problem/61117724>