Apple delivered a performance breakthrough Wednesday with its new A5X processor for the iPad, but it's possible that this chip won't make its way into the next iPhone, analysts said.The chips used in the first two iPads, the A4 and A5, both made their way into a new iPhone soon after. But the A5X, with its heavy focus on graphics, may not be ideal for smartphone use, and Apple may wait for a more power-efficient chip built with a new manufacturing process.The A5X has two CPU cores, just like the A5, and it was the superior graphics performance of the A5X that Apple played up at its launch event for the new iPad in San Francisco. The new chip has four graphics cores, which should boost multimedia performance and allow for smooth operation of the iPad's higher-resolution, 2048-by-1536-pixel display.Dean McCarron, principal analyst at Mercury Research, also sees the current A5X as an unlikely candidate for the next iPhone, which won't require as much graphics processing power as an iPad. The current iPhone has a display density of 326 pixels per inch, greater than the latest iPad's 264 pixels per inch, but the iPhone has only a 3.7-inch display.