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nvaccess / nvda

NVDA, the free and open source Screen Reader for Microsoft Windows
https://www.nvaccess.org/
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Bad performance in virtualBuffers for web pages with extremely busy javascript #514

Closed nvaccessAuto closed 8 years ago

nvaccessAuto commented 14 years ago

Reported by Agent Golder on 2009-12-22 11:47 Cases like www.greek-chater.com. After it has completely loaded it doesn't respond at all untill I switch to another application! Sometimes says things such as "Icon" and "Unknown object", new to me! And I setted the system to Windows 7 because I'M not sure about it in others... Again, I'M using the latest stable 2009.1 which isn't in the list. Any idea?

nvaccessAuto commented 14 years ago

Comment 1 by mdcurran on 2009-12-22 23:44 There does seem to be quite a lot of content updates on this page after the page loads. I'm not sure, but it seems to be quite a significant chunk of the page which keeps updating about once every second. (it may be the entire document), as NVDA is taking about 0.2 of a second to complete the update. However, its not NVDA updating its virtualBuffer which is slowing things down, as NVDA's performence with Firefox on this page is really bad even between updates. I guess this means that there is some very busy javascript on this page, either that or firefox is downloading a lot of content via xhttp or what ever. Note that things like nvda+f12 work fine, alt tabbing works fine, which means that its definitly Firefox which is slow.

Specifically, Firefox is taking a very long time to set focus to the object arrowed to with the virtualBuffer.

I'd be interested to know if a sighted user notices performance loss when tabbing or mousing around this page (with out a screen reader running).

Changes: Milestone changed from 2010.1 to None

nvaccessAuto commented 14 years ago

Comment 3 by mdcurran on 2009-12-22 23:48 Woops, changed wrong field. Fixing up Changes: Changed title from "NVDA freazes in "large pages"!!!! Please help!" to "Bad performance in virtualBuffers for web pages with extremely busy javascript"

nvaccessAuto commented 14 years ago

Comment 4 by Agent Golder on 2009-12-23 13:25 So what about now? Are you gonna fix it?

nvaccessAuto commented 14 years ago

Comment 5 by Steve Buell (in reply to comment 1) on 2009-12-28 18:35 Replying to mdcurran: The content which is continually updating is a visual effect of snowflakes (the 510 line "snowstorm.js") which reacts to the position of the mouse pointer. Very "1999" web design. This would probably be your culprit. There is also a lot more JS for user agent data collection, twitter posting, image resizing and some Yahoo user interface objects. This does not affect performance when tabbing or mousing without a screen reader running. The fault here lies with the site designer, not the assistive technology.

nvaccessAuto commented 13 years ago

Comment 6 by mdcurran on 2011-01-20 23:39 Due to last comment, really nothing we can do. Closing as cant fix. Changes: Added labels: cantfix State: closed