If you prefer a lightweight, open-source approach, Prism Launcher is the successor to the legendary PolyMC and MultiMC.
: Built with the Qt toolkit, it is extremely fast and allows for precise control over memory allocation and mod management. Extreme Launcher best minecraft client for low end pc
Perfect for a Core 2 Duo or AMD A-series APU. Just ignore the social features. If you prefer a lightweight, open-source approach, Prism