553968 - Animated GIFs run too quickly

Status: RESOLVED DUPLICATE of bug 232769

(Core :: Graphics: ImageLib, defect)

Description

[Kevin Israel]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2) Gecko/20100115 Firefox/3.6
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2) Gecko/20100115 Firefox/3.6

Animated GIFs, in Firefox 3.6, run about 2.4 times as fast as in Internet Explorer 8 (and Safari, etc.).

Reproducible: Always

Steps to Reproduce:
1. Open the above URL of a kaleidoscope animation in Firefox. You can use http://commons.wikimedia.org/wiki/File:Bouncywikilogo.gif as an additional test image.
2. Click on the image for a direct link.
3. Repeat steps 1 and 2 in another browser such as IE or Safari.
4. Install Greasemonkey and this user script: http://userscripts.org/scripts/show/72090 that slows down animated GIFs, multiplying all delays by a factor of 2.4.
5. Repeat step 1, observing the slowdown. (The script does not apply the slowdown to direct-linked images.)
Actual Results:  
The animation is noticeably faster in steps 1 and 2 than in steps 3 and 5. The 2.4x slowdown applied in step 5 causes the frame rate to approximately match that of Internet Explorer and Safari (which are about equal).

Expected Results:  
The animation should run at the same speed in all three browsers.