Find out how much RAM you have on your computer. Then look into changing how much am you give MC. Then go here https://www.youtube.com/watch?v=BiX6yRzW16w . Remember you only need to post the -Xmx (max ram). If you Computer has 3gb, use -Xmx1.5G. If you have 4gb+ use -Xmx2G. You can use G for GB instead of typing like 1500m for 1.5G.
