Moonchild Productions has launched Pale Moon 19.0 and Pale Moon x64 19.0 for Windows. Pale Moon is a customised build of popular web browser Firefox, with the developer making no attempt to keep pace with Mozilla’s six-weekly development cycle in favour of applying security updates and concentrating on delivering improved performance.

This release marks the first major update since Pale Moon 15.0 – based on Firefox 15 – was released last August, but while Pale Moon 19 utilises the brand new Gecko 19 engine found in the latest version of Firefox, don’t expect to see all the functionality in Firefox 19 making an appearance here.

With the underlying Gecko update, Pale Moon 19.0’s HTML5 implementation is more complete than the previous build. Javascript performance has also been improved thanks to the shift to the IonMonkey engine, which first appeared in Firefox 18. Also improved in Gecko 19 are the layout and rendering engines, but one side-effect is that users may have to update both add-ons and themes to retain compatibility with Pale Moon 19.

Minor cosmetic changes mask major underlying updates to Pale Moon 19.0.

While the overall layout of the browser hasn’t changed, there are subtle changes to the main browser controls and padlock icon.

Moonchild has – in accordance with its desire to produce a faster browser than Firefox – also applied specific tweaks to the rendering engine to improve performance, which it claims is noticeable both in general user and via certain unspecified benchmarks. These changes should help prevent browser stalls or high CPU usage on certain web pages.

Pale Moon 19.0 also abandons PGO (Profile Guided Optimization) in favour of global speed optimizations, which should give better smoothness regardless of which PC is using the browser.

As this is a custom build, don’t expect all of the functionality of Firefox 19 in this release. There are fewer developer tools, for example, while Moonchild has publicly stated the social API introduced in Firefox 17 won’t be appearing in Pale Moon.

The inline PDF viewer is present in Pale Moon 19, but switched off by default.

The inline PDF viewer is also apparently missing in this release, but that’s because it’s been switched off by default. Switch it on by typing about:config into the browser Address bar, then search for pdfjs – verify that pdfjs.firstRun is set to true, then double-click pdfjs.disabled so it’s set to false. Once done, you’ll be prompted each time you click on a PDF whether or not you want to preview it in Pale Moon. To make it the default choice, open Pale Moon > Options > Applications tab and change the Portable Document Format (PDF) entry to Preview in Pale Moon. Job done.

Pale Moon 19.0 and Pale Moon x64 19.0 are both available as freeware downloads for PCs running Windows XP SP3 or later, as are portable builds Pale Moon 19.0 Portable and Pale Moon x64 19.0 Portable.