Why is there so much lag?

well, mojang changed over a million lines of codes. There is so much more items/blocks that it causes lag. I been playing since 1.2.5 and 1.7 is what i call the "lag update".

Optifine 1.7

Optifine has updated for 1.7.2 and 1.7.4. Optifine is a mod (no forge required) that fixes bugs that causes lag and allows you to tweak the settings more. It can make it more fancy or more simple. you gain around 5-200+ fps (according to a poll) Optifine is also almost updated to 1.7.9.

Optifine foum: http://www.minecraftforum.net/topic/249637-174-optifine-hd-c7-fps-boost-hd-textures-aa-af-and-much-more/

Lag fix v 1.0 (1.7.4)

Lag fix is a little mod that I created. It changes settings like removing particles and fixing fixes.
Note: This mod will never update to 1.8 or whatever

Download: https://www.mediafire.com/?00589d4bwtacwu5

Cores (thanks to Creeper_Killer_X)

"* You can boost FPS by a good amount, by assigning Minecraft to certain cores.

- Contrary to popular belief, with Java 7, Minecraft can use UP TO 2 cores. It can fully utilize both of these cores to their max.
- So that means if you have a triple or quad core CPU, you can see huge FPS improvements from assigning Minecraft to run on certain cores. I have personally seen a 175 FPS increase on my desktop (used to get 256 and with this, I now get ~450+). + To assign Minecraft to certain cores, open up task manager. + From in here, go to "Processes" tab and find javaw.exe in the list of running processes. + Right click this javaw.exe process and choose "Set Affinity + From in this window you will see a list of your CPU cores. Uncheck them all and choose only leave 2 checked if you are on a quad core. If you are on a dual core, leave 2 checked too. Single cores should also do so, but to their one core."
-Crepper_Killer_X

Now from what i reed, uncheck all of them and ONLY check CPU 0.

Add more ram (from one of my older posts.. http://www.planetminecraft.com/blog/more-ram/)

do you want more ram? well this can help you...
go in your launcher.
press edit profile
put a check mark by the JVM Arguments
it should say -Xmx1G
change the 1 to a number you want. for ex. i want 2gb i change the 1 to 2 (dont add more than you have or will crash)

CODES

1gb -Xmx1G
2gb -Xmx2G
3gb -Xmx3G
and so on...

Programs to help fix lag (another one from my older post... http://www.planetminecraft.com/blog/minecraft-lag-fix-program/)

cleanup!

cleanup is a free program to clean your computer. dont worry it wont delete anything you need! itts a free to use program. it is optional to donate. DOWNLOAD:http://www.stevengould.org/index.php?option=com_content&task=view&id=15&Itemid=69

disk cleanup

this is a built in program for windows. so to start menu and search disk cleanup

Game booster

a program this stops some items to make your computer better for gaming.
DOWNLOAD (razer):http://www.iobit.com/gamebooster.php
DOWNLOAD (IObit Game Booster 3.4):http://www.techspot.com/downloads/4842-game-booster.html

Update your graphic card

If your graphic card isn't updated, games will lag a lot. Go to its website (I have an Intel HD 3000 so i go to Intel.com)
and update it.

Buy a new graphic card

so you tried updating it and everything but still lagging? Buy a new graphic card. I have an Intel HD 3000 and i get 30-50 fps. Don't buy Intel graphic cras, there more for watching videos and aren't good for gaming.

Play with a new clean minecraft

go to your .minecraft and delete it. Thren startup your launcher and it plays with a new clean minecraft.

Dont play with mods

Mods cause alot of lag. While so dont. So dont install mo' creatures that add a ton of mobs and items.

Tweak your settings