Performance of dojo (logging, comet, sliders)

Question

I have some performance issues in my JavaScript, and I'm not having much success instrumenting it. One of the things I've tried is using firebug's profile tool. It reports that the top single call was to dojo's log(). Unhelpfully, it reports a line number from the compressed script, so I can't tell what's causing the problem. But it seem interesting that 70% of the lines in the profile report are for dojo's log() calls, so cumulatively, it must be spending an amazing amount of time there. Is there a way to turn off dojo logging?

The only visible logging is an entry that shows up every 1.5 seconds and that appears to be a keep alive for comet. I'm also using dojo's slider in one place, but I don't see any evidence that that's causing a performance hit.

What other tools should I use to try to identify performance hot spots in javascript? The portion of my code that is in JavaScript is not really very large, so it wouldn't surprise me if it was round trips to the server that are really causing the problem, but I don't know how to instrument that either.

Answer 1

If you are using Dojo 1.2 or higher you can use stripConsole=normal while making your build to automatically strip all log calls it makes. If you are not using the build system then that's probably the #1 thing you can do to improve performance.

Some links to get you started:

http://docs.dojocampus.org/build/index

http://docs.dojocampus.org/quickstart/custom-builds

Answer 2

Try building your JavaScript too, using the Dojo builder. Also, remember that the slowest calls are DOM calls. So make sure you're not querying the DOM inside a loop when it could be moved outside.

Answer 3

You are likely using a compressed version of Dojo. If you change dojo.js to dojo.js.uncompressed.js, the profile information should show you much more accurate information.