According to the benchmarks, not true. The iPhone 6 & 6Plus are still the fastest. . . without even using iOS Metal which can give a huge graphics boost. Here are the graphics Benchmark results:
"Samsung's higher resolution Galaxy S6 (or equally high resolution Galaxy Note 4 "fablet") both turn in benchmarks significantly lower than Apple's existing iPhone 6 Plus—and less than half that of last year's iPhone 5s. In terms of fps, the latest benchmarks show that Samsung's new "Exynos 7" powered Galaxy S6 drops down to 15 fps—just 78 percent of the framerate of iPhone 6 Plus—in the same test.Looking at the competitive low-level theoretical scores of the GPUs Samsung uses (combined with much higher clock rates and more RAM), it appears that the company's devotion to extremely high resolution numbers is a spec list checkmark (rather than a real feature that benefits users) and is a primary contributing reason for poor real life scores in rendering 3D OpenGL scenes.
In other words, the chips Samsung is choosing to use could theoretically match Apple's latest iPhones if they were not also driving tons of additional pixels that contribute little to no benefit to users. Think of it as a reasonably powerful engine installed into a monster truck with massive wheels it can barely turn. . . . . .Using Metal, developers can achieve higher frame rates (and animate more details at any target frame rate) on the same hardware, allowing games on iPhone 6 Plus to further outpace competing devices in its category, widening the nearly 2x performance gap it already enjoys over Samsung's Galaxy Note 4 in generic OpenGL benchmarks. The slightly faster Galaxy S6 can't catch up because it is tasked with running a tablet-style resolution screen that it doesn't quite have the graphics power to drive."
SOURCE: Samsung Galaxy S6 delivers poor graphics performance vs Apple iPhone 6Plus — Daniel Erin Dilger — April 1, 2015 — AppleInsider