People familiar with the latest beta, dubbed 10H529, said Apple has asked developers to focus on 3D graphics, Mail, printing, QuickTime, and the X Windows X11 subsystems. The Delta Update is reportedly a 558MB download.
Apple already publicly released an update for the current version of its operating system, Mac OS X 10.6.4, this week in the form of the Snow Leopard Graphics Update. It improved performance in some popular game titles developed by Valve by as much as 120 percent.
The latest beta comes just 6 days after the previous build, 10H525, was seeded to developers. Apple was originally expected to begin seeding the first 10.6.5 builds to developers in July.
Mac OS X 10.6.4 was released in mid-June, packing fixes for trackpads on Apple's notebook computers, and also addressing issues with Adobe's Creative Suite 3. It also included Safari 5, Apple's latest Web browser.