In addition to all of the other features we’ve seen about Android 4.4 today, some news is breaking about a more performance-oriented upgrade; a brand new runtime compiler.
Before now, Android has always used the Dalvik virtual machine as it’s runtime compiler, and for the most part, it works well. However, in what’s probably a piece of Android’s new Project Svelte, they’ve introduced a new compiler called ART. This is likely related to Google’s big purchase of Flexycore not long ago, as these compilers relate directly to Android performance.
ART is showing up in some Android developer menus, but it isn’t completely implemented just yet. ART reads .oat files as opposed to the traditional .odex files that have been common in Android system applications up to this point. Android also includes an odex2oat converter, so whenever this does get implemented, it seems like Android should be able to handle the change as well as backwards compatibility with older data and apps.
This is some pretty technical low-level hardware stuff that most users never even notice, but if you’re interested, you can find out more at XDA in the source link.
source: XDA Developers