In the default install of Minecraft on the Mac you are using 32 bit java and the game warns that you can improve things by switching to 64-bit Java. I found a minecraft forum article that explains how to change things up to 64-bit here. The instructions also state that you’ll have to redo this every time you update minecraft and being lazy I decided to write out a script to make the changes for me. This is that script! All you need to do to use it is open Terminal.app (or your favorite terminal program, mine is iTerm2) and edit a new file, name it something like 64bitminecraft.sh. Then paste the script below into that file and run it by executing ‘bash ./64bitminecraft.sh’. If you’re new to shell scripting in unix here is a good introduction to shell scripting
# Perform Backup of all the files
if [[ ! -d ~/Minecraft_Backups/ ]];then
echo "Creating backup directory ~/Minecraft_Backups/"
mkdir -p ~/Minecraft_Backups/
tar -czf ~/Minecraft_Backups/`date +%Y%m%d`-backup.tgz /Applications/Minecraft/Minecraft.app
#Modify the Info.plist file for the new version of Java
if [[ -a /Applications/Minecraft/Minecraft.app/Contents/Info.plist ]];then
sed -i -e 's/1\.5\+/1.6+/' /Applications/Minecraft/Minecraft.app/Contents/Info.plist
sed -i -e '/I386/ c\
echo "Info.plist not found in /Applications/Minecraft/Minecraft.app/Contents/"
cp /System/Library/Frameworks/JavaVM.framework/Resources/MacOS/JavaApplicationStub /Applications/Minecraft/Minecraft.app/Contents/MacOS/</code>