By Slash Lane

Published: 02:00 PM EST

The next security and maintenance release for Apple's Leopard operating system could arrive sooner than later if the company maintains its current cadence, which has seen two successive pre-release builds land in the hands of developers in just five days.

On the heels of the first external test build labeled Mac OS X 10.5.3 build 9D10 and released privately late last week, the Mac maker on Tuesday followed up with build 9D11, which adds nearly 20 more fixes and code corrections, bringing the new total expected with software's release to nearly 100.

Among the most recent improvements, according to people familiar with the ongoing testing process, are fixes to AirPort connection issues and problems with the MacBook Air's sleep functionality.

Other fresh fixes target Time Machine, Spaces layering and preferences, graphics corruption, display issues within Mail.app, Back to My Mac communication issues, and Automator quirks when interacting with Mail.app.

As was the case with Friday's pre-release distribution, Apple reportedly asked that its developer community focus their ongoing testing efforts on two dozen core system components. These include, but are not limited to, AirPort, AppleScript, Audio, Dashboard, Directory Services, Dock, DVD Player, Finder, Graphics, Installer, Printing, and VoiceOver.

Mac OS X 10.5.3 Update, which currently weighs in at a hefty 410+ MB in Delta form and 530+ MB in Combo form, will mark the third update to Mac OS X 10.5 Leopard since the software made its official debut in late October.

While those people familiar with the ongoing testing process have been unable to provide a target release date, it's presume the update is being groomed for distribution sometime in April or May.