Dalvik, the virtual machine that runs almost every Android app, has remained virtually the same since day one -- and Dalvik is slow. Now, with Android 4.4, Google has revealed that a Dalvik replacement is in the works -- a replacement, called Android Runtime (ART), that should improve the performance of Android apps by a huge margin. The early version of ART in Android 4.4 already speeds up apps by around 100%, and the final version should be even better.