Firefox JavaScript performance on Mozilla's own Kraken benchmark. (Credit: Mozilla)

A JavaScript engine called IonMonkey, Mac Retina compatibility, and better touch support move into the new Firefox Beta, released today.

Firefox 18 Beta (download for Windows, Mac, and Linux) arrives with a new "just-in-time" JavaScript compiler called "IonMonkey" for faster site load times. While it doesn't appear to have been independently tested yet, Mozilla's own IonMonkey benchmarks from September indicate that it will make the stable version of Firefox 18 about 25 percent faster than the current Firefox 17. The features are expected to reach the Firefox stable channel around the first week of January.

Firefox JavaScript performance on Google's V8 benchmark. (Credit: Mozilla)

The new Firefox beta also allows you to disable insecure content at will on Web sites that have been secured with HTTPS. In the beta, the feature is only available through about:config.

The Mac version now works with high-definition Retina displays, and all Firefox Beta platforms support W3C touch screen-specific events, as well as MozTouch events.

Other changes include built-in viewing of PDFs, and early support for WebRTC, which eventually will let browsers run P2P apps, perform voice calls, and power video chats without plug-ins. Full notes on what's new in Firefox 18 beta can be read here.