I have tried a couple KitKat Roms (the latest being SlimKat back in March). Both ROMs had severe lag (Although SlimKat was a bit better) on bringing up the phone answer screen when a call comes in. I have been following the CM11 and SlimKat posts in the development section, but haven't been able to discern if this problem has been solved. I get the impress that it has been solved on the i9000, but so far have not seen any indication of a fix for Vibrants. Anyone know if the lag still exists. This is the one think keeping me on Jellybean.
XDA Developers was founded by developers, for developers. It is now a valuable resource for people who want to make the most of their mobile devices, from customizing the look and feel to adding new functionality. Are you a developer?