How to make minecraft run faster?

So as you see in the picture above, I have 4GB ram (3.6GB usable), AMD E-3000 APU with Radeon(tm) HD Graphics 1.30 GHz, and a 64 bit operating system. Well I only get about 15-20 FPS playing minecraft which is annoying and I want more. I heard to dedicate ram to minecraft and make minecraft the high priority but I'm not positive how to do that! Any help would be greatly appreciated!

For minecraft 1.6 or more

1.) Open up your MC launcher

2.) Chose the profile you would like to dedicate ram to then click edit profile

3.) Check the box JVM arguments

4.) It should say this -> -Xmx1G <- change the number to whatever so like -Xmx4G.

THIS IMPROVED MY FPS BY ABOUT 5 WHILE RUNNING SHADERS