The problem of Samsung Galaxy S3 to lag may not be so common, but if it does, here are some solutions. If there is a marginal delay when you press the Home button or when you exit an app, the lag may be attributed to your settings. In this case, do not use task killer apps and reboot your S3 to clear memory.
Simply drag down the notifications bar at the top and turn off Power Saving. No doubt, it is a good feature to save power, but it can also cause lagging. If you see that the problem with the S3 lag is due to the Home button, you may have to change some settings in the S-Voice. Double tap the Home button to initiate S-Voice and then go to Settings and remove the checkmark on ‘Open via the Home Key’.
Since animations can also cause lag in Galaxy S3, simply go to Settings – Developer Options and change ‘Windows Animation Scale’ and go to ‘Transition Animation Scale’ and turn it off or reduce it.