It looks as thought the US version of the Galaxy S4 from Samsung will sport Qualcomm's Snapdragon 600 processor, a quad-core part. While the US-based Galaxy S4 won't sport the octo-core processor we've heard about, the quad-core Galaxy S4 will have its four cores clocked at a higher frequency; 1.9GHz.
This means that the processor inside of the US version of the S4 will be the same as the HTC One and LG Optimus G Pro. The new Snapdragon 600 processor can provide up to 40% better performance than its predecessor, the S4 Pro. The new Snapdragon 600 SoC also includes a new version of the Adreno 320 GPU, as well as LPDDR3 memory support. The international version of the Galaxy S4 will sport the octo-core processor, clocked at slower speeds, but they will be more power-efficient.
At times when the smartphone requires more processing power, the faster cores will come into play, boosting the processing power with their Exynos 5 architecture.