If you also have Circuitous, this is perfect. If not, install libdisplaystack in Cydia. Anyways, if you have already done the above (or you already have Circuitous enabled), go to Settings. There should be an option called DisplayController, choose it. Then make sure "Override animations" is On and "Animations" is off. Now enjoy instant app launching and quitting. Seriously, I have never ever in my life seen any computer do it this fast!!