MultiMC5

MultiMC5 is a custom launcher that allows multiple Minecraft
instances installed at once.

Add OptiFine to a Minecraft instance

OptiFine is a Minecraft optimization mod.
This guide shows how to add optifine to an instance on windows.

• If not already done create an instance on MultiMC5
• Download the according version of OptiFine from their website
• Open the Minecraft standard (Java) launcher and start the according version at
  least once
• Open the OptiFine jar, click Extract and save the extracted OptiFine to a folder
• Edit the according instance and select Version, then select Add to Minecraft.jar
  and select the extracted OptiFine