Google has just announced Android 4.1 Jelly Bean during their Google I/O 2012 keynote. Jelly Bean brings a whole bunch of cool new features, including offline voice typing, improved handling of widgets on the Android home screen, and more. Jelly Bean also brings some big under-the-hood improvements to Android. Project Butter is designed to drastically improve the speed and smoothness of the Android interface.

Noting that the human visual cortex is extremely sensitive to delays, Google made some major changes to the way Jelly Bean handles system resources in order to increase the framerate and improve the overall smoothness of the UI. With Jelly Bean, the CPU, GPU and device display run in sync with one another, which allows the rendering framework to run much more smoothly. The touchscreen interface is also improved. Now, rather than waiting for the display to refresh after you touch the screen, your device anticipates where your finger is going to be and responds almost instantly to the input.

Project Butter also improves the CPU’s response to touch events by eliminating the time needed to spin the CPU’s frequency back up upon detection of a touch.

During the keynote Google showed off Project Butter’s improvements in a high speed video that showed a Galaxy Nexus running Ice Cream Sandwich next to one running Jelly Bean. The Jelly Bean device had a much higher framerate and much smoother animation.

The Project Butter improvements apply system-wide and to all apps. Google will hold a session – titled “For Butter or Worse” – during the conference tomorrow to help developers get a handle on what Project Butter means for developers.