1322684 - DOM traversal 5X slower than bookmarklet or Chrome extension

Status: RESOLVED WONTFIX

(Core :: DOM: Core & HTML, defect)

Description

[tinebak]

Attachment: tryrun.js

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.99 Safari/537.36

Steps to reproduce:

I created a simple script (attached) that traverses the DOM of a webpage and looks up the computed styles of the elements.

I ran this script in three ways:

1) Firefox bookmarklet
2) Chrome extension
3) Firefox extension

The Firefox extension loads and executes the script when the user click the browser button.

Firefox background page:

browser.browserAction.onClicked.addListener(function(tab) {
     browser.tabs.executeScript(null, {file:"tryrun.js"}); 
});

I measured the time to execute the traversal, which does not include time to load the extension/bookmarklet, etc.


Actual results:

The Firefox extension is really slow compared to the other methods. I ran it on the following basic webpage: http://www.bbcgoodfood.com/recipes/3256/moroccan-lamb-with-apricots-almonds-and-mint

Times:

Chrome extension:    250 ms
Firefox extension:    1550 ms
Firefox bookmarklet: 400 ms




Expected results:

It should have been faster. Unfortunately this means that I cannot create my tool as a Firefox extension. Once I include the extension's other code the extension can take more than 5 seconds to execute. This is not acceptable to my users.

Comment 1

[Bas Schouten (:bas.schouten)]

This bug is quite old and most parts involved here have been changed since the original report. If we have real world cases of this happening we should make sure a new bug is filed containing them.