There's two things here. One is the lag we can fix, and one is the one we can't.

The lag we can fix is from Samsung implementing the 'double tap home button to use voice command' feature. Because of this, the phone always waits 0.5 secs for a second click. The new cognition removed this feature and thus the lag from this.

The other issue is just the phone needing time to process and render your click/homescreen. If your homescreen is loaded with widgets, don't expect it to be lag free.

Its not always going to be in the app drawer. Never tried litening, but for cognition, its not in the app drawer. Either use the extended power menu, or off the phone and boot into recovery mode using the hardware keys.

If you flashed to another stock kernel, chances are your CWM will be gone. I think you should have flashed the zimage of a stock kernel, not the kernel itself. After that, flash the zimage of a CF-Root kernel.

Anyway, my point earlier is that the CWM app might not always be present in the app drawer. It doesn't mean you don't have CWM. You can still access it thru the power menu (hold down power button, select recovery), or using the hardware keys when the phone is off (should be power+menu+volume up). Since you're flashed a stock kernel tho, I think you'll need to reflash a CF-Root kernel.