Another thing you can do is:
Step 1. Open Minecraft
Step 2. Open Task Manager
Step 3. Find the process "javaw.exe"
Step 4. Right click on "javaw.exe"
Step 5. Find "set priority"
Step 6. Scroll over it a little drop out box should appear
Step 7. Set the priority to high (Never set it to realtime it will crash your computer!)
Step 8. A little window will pop-up asking you if you are sure you want to change the priority of "javaw.exe"
Step 9. Just click change priority in the little window.
Step 10. Play Minecraft with no lag!!!
PS. You have to do this everytime you open Minecraft but it will greatly increase your performance. Use this aswell as the other suggestions