The Qualcomm Snapdragon 875 might have a secret weapon against the Samsung Exynos 2100: ARM's latest X1 cores
Tipster @UniverseIce recently claimed that only the Qualcomm Snapdragon 875 will feature ARM's latest X1 high-performance CPU core. If true, this would put Samsung's home-grown Exynos 2100 at a significant disadvantage in terms of single-threaded performance. This could lead to the upcoming Samsung Galaxy S21 Plus trailing behind competing flagship devices in benchmarks.
Both the Snapdragon 875 and Exynos 2100 feature a heterogenous CPU design, with one large core, paired with performance and efficiency cores. The Snapdragon 875 will likely utilize a single X1 as its large core, for optimal single-threaded performance, together with a number of ARM A78 and ARM A55 cores.
Initial reports suggested that Samsung would utilize a similar core configuration with the Exynos 2100, with the large core clocked at nearly 3 GHz. If @UniverseIce's claim pans out, Samsung might simply utilize a higher-clocked A78 as the "large" core, together with 3 lower-clocked A78s. The X1 itself is based on the ARM A78 architecture but redesigned to maximize performance over power efficiency. ARM claims a roughly 30 percent performance uplift over the A77.
We don't know exactly how much faster it is relative to the A78. However, significant differences in IPC could translate into a big gap in performance between Exynos 2100-equipped devices and devices that ship with the Snapdragon 875.