Like the prior Cortex-A77, the Cortex-A78 will consist of what ARM calls its big.LITTLE octacore architecture, with four high-performance A78 cores and four A55 cores optimized for long battery life. ARM said that a Cortex-A78 core running at 3GHz would deliver 20 percent more sustained, single-core performance than the Cortex-A77 core running at 2.6GHz, assuming 1 watt per core. The performance is based on simulated estimates. Alternatively, a phone maker could clock the A78 to consume half the power at the same performance as the A77, Williamson said. ARM believes that the octacore Cortex-A78 layout will require 15 percent less die space than the Cortex-A77, leading to smaller phones.