471817 - Slowdown using tab key to change focus on very large forms

Status: RESOLVED WORKSFORME

(Firefox :: Keyboard Navigation, defect)

Description

[B.J. Guillot]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.0.5) Gecko/2008120122 Firefox/3.0.5
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.0.5) Gecko/2008120122 Firefox/3.0.5 

I'm attaching an example.  It's a large form with hundreds of div's (most of which are hidden).  All these are inside numerous tables.  Firefox (3.0.5 for Windows 32-bit) seems to slow down significantly trying to determine which control should get focus when hitting the 'tab' key.  The controls are NOT using TABINDEX attributes.  The slowdown does not start occurring until you get past the tenth row or so in the example.  The problem does not occur with 3.0.5 on Linux x86_64, nor other browsers on Windows such as IE7 and Chrome.

Reproducible: Always

Steps to Reproduce:
1. Unzip the attached file and bring up the ff_bug/ff_tabs.html test case in the Firefox 3.0.5 browser running on Windows.
2. Hold down the 'Tab' key to quickly change focus from one widget on the form to the next (over and over again)

Actual Results:  
Firefox (for Windows) rapidly changes focus from one element to the next until it hits the 10th line in the table.  After that point,
the browser freezes for several seconds when hitting 'tab' to move focus to the next widget.


Expected Results:  
I expect Firefox for Windows to at least keep up with IE, Chrome, and FF for Linux.  There shouldn't be any delay when hitting 'tab' to change focus.


Note: I also tested this against the FF beta for Windows:
Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1b2) Gecko/20081201 Firefox/3.1b2 
The 3.1 build ran much faster than the 3.0.5 build, but had a minor slowdown around the same place.

Note: I also tested the same case against the following browsers with no slowdowns:
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.0.5) Gecko/2008121911 CentOS/3.0.5-1.el5.centos Firefox/3.0.5
Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Tablet PC 1.7; .NET CLR 1.0.3705; .NET CLR 1.1.4322; .NET CLR 2.0.50727)
Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US) AppleWebKit/525.19 (KHTML, like Gecko) Chrome/1.0.154.36 Safari/525.19

Comment 1

[B.J. Guillot]

Attachment: Demonstrates slowness issue when holding down tab key to change focus

Comment 2

[Nochum Sossonko [:Natch]]

Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9.0.5) Gecko/2008120122 Firefox/3.0.5
Can you post a reduced testcase (ie a single html file that shows this bug)? This works for me as is.

Comment 3

[u88484]

This also WFM.  Please reopen if you can reproduce in safe mode and if you can attach a reduced test case.