We've heard rumors before that Samsung has a few versions of the handset with different Exynos and Qualcomm silicon in the lab, and it might be that the S IV has been greenlit with Qualcomm's finest instead of the homebrew Exynos brand.
It is indeed hard to beat the Snapdragon family when it comes to system-on-a-chip performance, as the chipsets come with the baseband radio that covers most of the world's networks integrated as well.
The new HTC One rocks a Snapdragon 600, clocked at 1.7 GHz, and we saw the alleged Galaxy S IV leak a few times already with the carrier versions GT-I9505/SHV-E300S/SHV-300L/SCH-I545 sporting Adreno 320 GPU and the CPU clocked at 1.9 GHz, which is precisely the maximum reported frequency for the quad-core Qualcomm processor with four Krait cores.
Not to complain, though, as the benchmarks from Snapdragon 600 are coming back north of 12, 000 points on Quadrant, which means there won't be a task or an app to slow it down. This rumor is also certain to send Qualcomm's shares through the roof if it holds water, considering the many millions of sales expected for Samsung's 2013 battleship.