According to AppleInsider, Apple has begun testing the next update to Safari 4, Safari 4.0.5, QuickTime 7.66 and a pro applications update.

Safari 4.0.5

According to the report, the major focus of the update is to fix an issue with the browser’s JavaScript engine, which was caused by the 4.0.4 update. The update will also reportedly see certain code blocks, like Move Code, transitioned from the Safari codebase to that of Webkit in order to improve cross-platform support.

The early builds of Safari also include improved HTML 5 video playback, quicker loading of the Top Sites panels, faster JavaScript performance, better performance loading YouTube, and an overall reduced memory footprint.

Finally, there seems to be a much improved plugin manager, which is now aimed at protecting Safari crashes and freezes caused by the Adobe Flash Player plugin.

Safari 4.0.5 is currently in testing under the following operating systems: Windows, Mac OS X 10.4 Tiger, Mac OS X 10.5 Leopard and Mac OS X 10.6 Snow Leopard. Each are members of the 405Axx build line and weigh in between 26 and 38 MB.

QuickTime 7.66

According to the report, Apple is also testing a maintenance, security and performance update for QuickTime 7, titled QuickTime 7.66. It is said to be the final update to QuickTime 7 and is currently in testing under Windows and Mac OS X Leopard. The current build is reportedly build 23.

Pro Applications Update

Finally, according to the report, Apple is also wrapping up QA testing on a major maintenance release to its Final Cut Studio and Pro applications labeled “Pro Applications Update.” Some people that helped test say it was originally scheduled to go live last week but has been pushed back.