You can't remove the bloat unless you root it. Best thing you can do for the phone is root it. Mine had lag in various places that drove me bat shit crazy until I remove it. One other thing you can do is disable S-Voice from coning on when you double tap home button. There's lag in the single tap because it's waiting to see if you are going to double tap.
If you want a suggestion and don't want to get fancy, root the phone, install CleanRom, whatever version he's up to now and enjoy. If you do not want to install a diff rom, root it and install Ti-backup and remove all bloat.
Here's a list of all the things you can freeze or remove w/out breaking something. I do not suggest all of them, but most.
http://www.info-stuff.com/2013/05/galaxy-s4-safe-to-freeze-apps.html