By Daniel Eran Dilger

Published: 05:00 PM EST (02:00 PM PST)

Apple has stopped bundling Adobe Flash on new Macs, ostensibly so users could obtain the latest, secure version themselves, but vastly increased battery life seems to be another leading reason.

According to testing performed by Chris Foresman of Ars Technica, the new MacBook Air can last for a full six hours after loading a series of webpages in Safari, but its battery performance drops down to four hours once Adobe Flash is installed and the same sites are loaded.

"Flash-based ads kept the CPU running far more than seemed necessary," Foresman wrote. Without the Flash plugin installed, websites typically display static ads in place of Flash content, erasing the need for constant processing power demanded by the Flash plugin's rendering engine.

With Flash ads consuming as much as 33 percent of the MacBook Air's battery potential, it's no wonder why Apple has demonstrated no interest in getting a version of Flash installed on its iPad, iPod touch and iPhone, all of which have much smaller batteries.

This summer, Adobe launched a public relations attack on Apple for failing to support Flash on its iOS devices, nor allowing Adobe to deliver a version of Flash for the iOS platform, nor approving apps for the iOS that were created in Adobe's Flash Professional application. Apple has backed away from refusing to approve apps created with third party tools, but has shown no interest in getting Flash content to run on its iOS.

When asked for "any updates" on the company's stance on Flash during its quarterly earnings report, chief executive Steve Jobs quipped, "flash memory? We love flash memory," before taking the next question.

Apple's removal of Adobe's Flash plugin from a default install on the new MacBook Air coincided with the company's debut of a more conservative new "wireless productivity test" it said was more in line with actual use, and better standardized for accurate comparisons between models. Being able to test the new machine without its battery being taxed by Flash ads certainly helps the company achieve better results.

The Shrinking Flash Platform

Microsoft stopped bundling Adobe Flash with the release of Windows Vista in 2007, although its motivation was likely due to the company's efforts to push its rival Silverlight plugin. However, Windows implements Flash as an ActiveX control, which means users can click on Flash placeholders within a webpage and the Flash plugin will install itself. New Mac users will have to manually download and install Flash from Adobe in order to make it available.

Apple sells far more iOS devices than Macs, and no iOS devices support runtimes for Flash content. That has had a major effect upon advertisers, publishers, website design, and online video broadcasters, who have collectively made monumental shifts away from Flash. This in turn has made Flash playback far less important on the desktop than it was just a year or two ago, although there is still important content tied to Flash.

Apple has removed Flash content from its own website, although it also has supported Adobe's efforts to add hardware acceleration to the Mac OS X version of Flash, and has approved the Skyfire plugin for iOS' Mobile Safari, which uses a gateway service to translate Flash videos into HTML5 videos that can play on Apple's devices.