Why my minecraft is so laggy?

Maybe your hardware is weak.

Compare your PC specs to minecraft's minimum requirement.

Probably because of your computer not being able to handle it. Try these steps to make it more smooth.

1.Download optifine and put everything at the lowest possible and keep increasing the quality until you start lagging. Optifine is a mod that optimizes your Minecraft to make it more smooth.

2.Use OCD resource pack. It is lower quality than the default resource pack and will provide easier graphical processesing.

3. Try putting more ram in. On the Minecraft launcher click edit profile and tick the JVM arguments box at the bottom then put in these exact words.

-Xmx2048M -Xms2048M

Once you have put that in press save.

4. Make sure you aren't running any programs you aren't using.

5. Make sure you have plenty off space left on your hard drive. Check this by going to start menu then computer. If the bar is red you need to free space. If it isn't you are fine.

Doing these will greatly improve your performance. Hope I helped!

http://www.game-debate.com/...=Minecraft
Put in your specs here. RAM, CPU, and GPU are what makes the game good.
I would recommend about 4gb of RAM, an i3 CPU with optifine, and for GPU look around google and search for cheap GPU's for Minecraft.