Like with most SoC upgrades these days, greater gains are seen on the GPU side than the CPU side. This is true of the Snapdragon 615 and its Adreno 405, which focuses on rendering to 1080p displays where older SoCs have focused on lower resolution displays.
Starting with the good stuff, the Adreno 405 smokes the Adreno 305/306 in the Snapdragon 400/410 by a whopping 175% on average, which equates to a 40% advantage onscreen when factoring in the jump from a 720p to 1080p display. This basically means you’ll achieve better frame rates in intensive 3D games on a Snapdragon 615 device like the Oppo R5, even with a higher resolution display.
On the other hand, the Adreno 405 is 3% slower than the Adreno 320 in the Snapdragon 600, which is a marginal difference that keeps the two SoCs trading blows. However it gets blown away by newer flagship SoCs such as the Snapdragon 810, which focus on 1440p displays and are up to 300% faster on the GPU side. The more modest Snapdragon 801 is also twice as fast.
NAND speeds are interesting, with the Oppo R5 performing very well in both sequential and random writes, at least compared to many of last year’s flagships. However it is let down by read speeds, which are below bar, especially when it comes to random reads.