Factory reset and/or reflash the rom with odin, disable all the bloatware and use nova launcher. Without root you can't disable everything but it should be more fluid.
An extra lite custom rom, based on stock, is the same to use but without any bloat. On mine I have at 500mb free after clearing memory in samsung task manager, but seldom have the need to do so.
Note: This quote doesn't automatically apply to everyone, decide for yourself if it might apply to you.
Originally Posted by justruss
What has this place become?
It's essentially a few people graciously answering the same repeating of immature, lazy, demanding questions from the masses.
Nobody searches. Nobody reads the first posts or titles of threads. Nobody even looks at posts a couple above their own.