Graphics, Throttling and Storage Performance
The X Performance and its Snapdragon 820 include a powerful Adreno 530 GPU which performs just as well as other Snapdragon 820 devices I've reviewed. The one difference here is that the X Performance uses a 1080p display, whereas the HTC 10 and LG G5 that I reviewed previously use 1440p displays.
Compared to these 1440p devices, the X Performance boasts 60% better on-screen performance due to the lower resolution. The Adreno 530 is already capable of playing all the latest Android games at 1440p, so I didn't experience any real in-game performance advantage at 1080p. However, if more graphically intense games get released in the next few years, the X Performance will be more suited to tackle them than its 1440p competitors.
Upgrading from an older device? The X Performance outperformed the Snapdragon 810-powered Xperia Z5 by 51% in on-screen graphics tests and outperformed the Snapdragon 801-powered Xperia Z2 by more than 150% (both are 1080p handsets).
The Xperia X Performance does not exhibit as much throttling as competing Snapdragon 820 devices, although this comes at the expense of heat, as this smartphone can run hot.
NAND performance is good, as you'd expect from a flagship device, trading blows with its competitors in sequential and random throughput.