Many players use OptiFine for better in-game performance.
Find the appropriate download for your game version HERE, and the homepage to their website HERE.

Note that you will have to start Minecraft at least once in the version you are using before you can use it with OptiFine. If you play the game in different game versions, you will need to download OptiFine for each of those game versions separately.

The installation instructions are straightforward: after downloading the appropriate .jar file for your game version, just double-click it to install OptiFine.
You can tweak everything to your taste via your Minecraft in-game settings.