Sidr - A jQuery plugin for creating side menus
berriart.com
berriart.com
Taking a look at the source, it should use CSS translateY instead of javascript animation, would perform much better specially on mobile devices.
CSS transitions are the method for this. Not without their own caveats, but usable. I've written extensively on the subject with this exact implementation of an off-canvas menu: http://coding.smashingmagazine.com/2013/01/15/off-canvas-nav...
CSS transitions/transforms let the browser render once on separate layers. The animation frames can then be composited faster (and accelerated on the GPU).
Paul Irish has a great demo: http://paulirish.com/2012/why-moving-elements-with-translate...
It does beg some questions about using it in non-touch scenarios though. The experience with a mouse isn't the best right now because everything moves.
Would be curious about the menu having a close button of its own, in the exact same position that the "Menu" you would have clicked to open it was in.