For the lightest bow you can try the High Country carbon fiber riser compounds. They come in rigged at well under 4 pounds but they kick like a mule. It's super light but I don't feel the quality is all there yet (limbs, limb pockets and coating need work). I'd prefer either the BowTech Tribute or Allegiance, as mentioned by others. They have about a pound more weight but the quality is much higher and they shoot a lot smoother. For true weight savings, shoot a longbow!