 Nehalem-based microprocessors use the 45 nm process, run at higher clock speeds, and are more energy-efficient than Penryn microprocessors.Hyper-threading is reintroduced, along with a reduction in L2 cache size, as well as an enlarged L3 cache that is shared among all cores.Nehalem was replaced with the Sandy Bridge microarchitecture, released in January 2011.