Mozilla has released a fifth beta for Firefox 4, adding hardware acceleration in Windows, a new audio API and support for a new security protocol.

You can download Firefox 4 beta 5 from the Mozilla website, or, if you’re currently using beta 4, head to the Check for Updates menu item to update to beta 5.

The most obvious change for Windows users will be the hardware acceleration, which should make Firefox considerably snappier. While beta 4 included support for hardware acceleration on Windows, it was not enabled by default. Beta 5 gives users hardware acceleration out of the box (provided you’re using a version of Windows that supports DirectX 10).

Like we’ve seen in the most recent graphics-intensive games on Windows PCs, the idea behind hardware acceleration is to shift some of the work from your computer’s main processor to the graphics card. In a browser, this speeds up page rendering, particularly text, graphics and scripted animations. The coming Internet Explorer 9 and future versions of Google’s Chrome browser will both take advantage of hardware acceleration.

The other major new feature in this release is a new Audio Data API that gives web developers a way to interact with raw audio data in HTML5′s <video> and <audio> elements using JavaScript. With the new API, developers can read and write audio data within the browser, opening the doors for online tools like spectrum analyzers, audio remixing tools and 3D audio visualizations.

For more on what the audio API offers, check out our earlier write up and be sure to read through Mozilla developer Dave Humphrey’s blog post. To see the new tools in action, check out the video Humphrey created to showcase some of what’s possible with the new audio API.

The Firefox 4 beta also now supports the Strict Transport Security (HSTS), a new security protocol that allows websites to require that Firefox always use secured connections. Designed to help stop the so-called “man in the middle” attack — where something lurking between your browser and the secure website steals your data — Firefox 4 Beta now remembers which sites use the HSTS protocol and will only connect to those sites using SSL in the future.

See also:

• Fourth Firefox 4 Beta Adds ‘Panorama,’ Hardware Acceleration
• New HTML5 Tools Make Your Browser Sing and Dance
• SamplePlayer Makes Your Browser Sing, Sans Flash