OK, so I run minecraft on a $130 laptop, and thus as you can expect that I lagged to the nether and back. But, I optimized my laptop to be a gaming computer, and now I can finally play MC like it should be. Here's how: (the programs used in this tutorial are all completely freeware, but you can buy premium versions of them if you like.)

Step 1: Install Optifine, It's a mod for minecraft that gives you a lot more video settings to help make MC look awesome and run smoother.

Step 2: Get Game Booster here: www.iobit.com/ (I recommend you use all of Iobit's software, they kick arse!)

Step 3: Run Minecraft with game booster

Step 4: Enjoy virtually lagless minecraft! (and other games, as Game Booster helps all of them.)

Bonus:

• You can also dowload advanced systemcare from iobit to speed up your computer overall.
  
• Ramdisk is also an option that makes a virtual disk on your computer which you can put your files in to speed them up. Be warned, if you have a small amount of ram like 2GB or so and/or devote too much memory to it, this will make your computer run MUCH slower except for the files you put the on "disk".
  

I highly recommend this for everyone and hope the post helped, if so, spread the word :)