498261 - -moz-transform rotated and scaled nested elements render very slow with high cpu

Status: RESOLVED INCOMPLETE

(Core :: General, defect)

Description

[caseygiles]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US) AppleWebKit/530.5 (KHTML, like Gecko) Chrome/2.0.172.31 Safari/530.5
Build Identifier: Firefox 3.5 beta 4

When rotating and scaling an element with the new -moz-transform with wrapper element containing many elements (eg 20 x 20 grid of div elements containing images) the page is very slow to render and CPU spikes very high. Especially when compared to all browsers supporting -webkit-transform

Reproducible: Always

Steps to Reproduce:
1. Produce test page with nested elements inside a wrapper element which you rotate and scale. 
2. To repeat test change an element dynamically with javascript, causing a re-draw you will see the CPU spike and render speed crawl. (esp on low end systems)
Actual Results:  
CPU usage spikes high, slow to render page (number of seconds)

Expected Results:  
Perform in a more timely fashion, as do competing browsers

Only tested in windows XP but assuming performance similar in other OS.

Comment 1

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Did you have a URL for the test page, or could you attach it to the bug (See "Add an attachment" above)?

Comment 2

[Ryan VanderMeulen [:RyanVM]]

Casey, do you have a link to a site showing the performance problem?

Comment 3

[Wayne Mery (:wsmwk)]

lacks testcase