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Firefox 19 was last month released in beta but already Mozilla is pushing out the finished version of the browser. The most notable new feature with Firefox 19 is a new, built-in PDF viewer to ward off the potential for security exploits due to PDF reader plugins. Speaking about the new feature last month, Bill Walker and Brendan Dahl, Mozilla Engineering Manager and Software Engineer, said that the feature was driven by a desire to push the boundaries of HTML5.
"For a number of years there have been several plugins for viewing PDF's within Firefox," they said. "Many of these plugins come with proprietary closed source code that could potentially expose users to security vulnerabilities. PDF viewing plugins also come with extra code to do many things that Firefox already does well with no proprietary code, such as drawing images and text. These problems, and the desire to push the boundaries of the HTML5 platform, led Andreas Gal and Chris Jones to start a research project they named PDF.js. The project quickly picked up steam within Mozilla Labs, where it grew into a full-fledged PDF viewer."
Firefox 19 also boasts start up performance improvements, Remote Web Console for connecting to Firefox on Android or Firefox OS, a Browser Debugger for add-on and browser developers, as well as bug fixes.

Also good to know about the built-in PDF viewer. I had switched from Adobe Reader to Foxit Reader, and to maximize performance and security within the browser I had even disabled the plug-in, so that Firefox would request to open the main Foxit application to open the file, it will be interesting to see how their HTML5 implementation works, both from a performance and a security point of view.
Go ahead and try making your own PDF reading program and see how *easy* it is. There's nothing wrong with that being the major feature for a new version. Heck, I don't think that it'd make much sense to not make a new version to start off a feature like that. Besides ,there were several other important features along with the regular performance enhancements and bug fixes that one expects with a new version.
Javascript is required to log into Tom's. There is absolutely no good reason to be posting on Tom's articles if you can't stand Javascript, which is relied on for many websites to work properly.
I have over 40 tabs open in FF right now. It's using about 200MB total. Perhaps you have other issues, especially since your experience is not normal.
More details would be needed to verify or refute what he says, as memory usage depends from pretty much everything, excluding weather.
- what did he use to measure memory usage? (task manager is not ideal for this for reasons)
- what add-ons and extensions can be found on his IE and Firefox
- what sites did he use
Even with FF18 if I look at something on youtube the sound will play fine but nothings happening visually then a fww seconds later it will change to that frame but still no movement, it takes about 30 seconds or so before the video is displaying and running fine which it then runs fine untill it's finished but about 90% of video I look at (youtube, somewhere else, embedded or not) have this problem at the start of the video.
On the other hand if I view it in IE there's no problem at all. Everytime i get a new FF I tryit for a while but I always end up just using IE anytime i'm looking at a video :s
Flash works in FF for me. read about many people saying they have issues, but I don't, so that seems to imply the the issue is not FF or at least not entirely FF.
400 tabs open right now in waterfox 10 the firefox 64gb ff varriant, 1.39gb
32 tabs in chrome, little over 4gb when all is added up.
opera is about 50-100mb per tab open, but as i only use that to upload to youtube and a secondary pastebin account it doesn't matter.
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