For eager beavers who want a taste of Firefox to come, Mozilla issued a second preview release Wednesday of the browser.

The software is based on version 1.9.3 of the Gecko browser engine that underlies Firefox. The current Firefox 3.6, and an update called Lorentz, are based on 1.9.2.

The headline feature of the new preview release is the same for Lorentz, though: out-of-process plug-ins, which means that Adobe Systems Flash Player and the like run in a separate memory compartment to protect the browser overall when they crash. Mozilla hopes people will see how well it works on an OOPP testing page.

However, according to a mailing list posting by Benjamin Smedberg, who’s working on the OOPP feature, it only works on Linux and Windows systems at present. “MacOS presents some unique challenges: the traditional drawing and interaction model for plug-ins is very difficult to do across processes. We are working on Mac support for multi-process plug-ins, and hope to have a preview of this work available soon,” Smedberg said in an OOPP blog post.

The new alpha release also should cool off some hot spots that consume a lot of labor when laying out Web pages, Smedberg said, thereby improving performance.