This tutorial will show you how to launch Minecraft with more RAM on Windows 7. What this does is increase the heap size of the Java Virtual Machine. With this way there is no batch files or editing run time variables.
1. Right click on the desktop. Select New Shortcut.
2. In the box type javaw -Xmx?G -jar "C:\?????\Minecraft.exe"
"-Xmx?G" is how many Gigabytes your Minecraft will launch with (ex. "-Xmx4G")
"C:\?????\Minecraft.exe" is the path to your Minecraft Launcher (In my Case its"C:\Users\Coleman\
3. Click Next.
4. In the box type a name for the shortcut (ex. "Minecraft")
5. Click Finish.
6. By default the shortcut will have the Java logo. To change this right click on the shortcut and select properties from the drop down.
Near the bottom will be a button labeled "Change Icon..." click this then
click the button labeled "Browse...". Navigate to where your "Minecraft.exe" is located. Select it then press "Open".
Click "OK" then click "Apply" then click "OK". The shortcut should now have the Minecraft logo.
7. To launch Minecraft simply double-click on the shortcut like you would do with any other program.
You may also use "-Xmx?m" to specify a heap size in Megabytes.(For common sizes see below.)
One Gigabyte: "-Xmx1024m"
Two Gigabytes: "-Xmx2048m"
Three Gigabytes: "-Xmx4096m"
Four Gigabytes: "-Xmx8192m"
*NOTE: Only users with 64 bit Windows will be able to use more than 4GB RAM. Unless your computer has more than 4 Gigabytes RAM do not allocate more than 2 Gigabytes.
I used this method (and another of other methods including making a .bat file) and it will launch minecraft succesfully, and when I hit f3 it shows that I have indeed allocated the desired memory to minecraft, but for some reason I experience dramatic frame rate drops compared to vanilla Minecraft which runs fine on my computer. Do you have any idea why this is the case? (I've tried allocating more or less RAM and I know I'm not using more RAM than my system has. Sometimes I'll try it with only 20% of the RAM my system has and I still experience frame rate drops).
First a few questions:
How much RAM does your system have?
How much are you allocating?
Are you using any mods?
Sometimes if you allocate to much memory it will slow down but it shouldn't drop frames. One of the things you can try is to use the mod Optifine. This mod makes Minecraft run better by using your computers resources more efficiently. Generally Minecraft allocates 512 MB of RAM, less than that may be unstable.
Also in your response please include your system specs. You can view you specs by going to the start menu, then searching for "Performance Information and Tools". You can either copy and paste them or take a screenshot.