LG's decision to use the Qualcomm Snapdragon 808 for the new LG G4, announced earlier today, rather than the Snapdragon 810 as it had used in the LG G Flex 2, has surprised a number of industry commentators. This combined with the fact that the 808 is, on paper, a lesser processor and the 810's reputation for overheating, has caused Qualcomm to announced that LG's decision to use the Snapdragon 808 was taken over a year ago. Qualcomm spokesman, Tim McDonough, said this on the matter: "The decisions on which chipsets to put on which handsets come from over a year ago." It appears that Qualcomm are on something of a charm offensive because of the reports regarding the 810's thermal issues. Tim goes on to explain that LG picked the 808 because it would be available by the time the G4 was due to be released, whereas the LG G Flex 2's timing meant it needed the Snapdragon 810.
However, in real world performance terms I would not be surprised if the Snapdragon 808 offers at least comparable performance to the 810 most of the time. The significant differences between the two processors stem from the 808 using a big.LITTLE architecture based around a high efficiency quad core Cortex-A53 processor backed up by a high performance dual core Cortex-A57 processor, and the 810 using a similar high efficiency quad core processor and a lower clocked, high performance A57 core. There are also differences between the GPU of both processors but as detailed information is not yet available about the 808's GPU it is difficult to determine how significant these will be.
There are two reasons why the 808 has a very realistic chance of offering comparable performance. One is that the dual core A57 is believed to offer a higher clock speed compared to the quad core unit in the 810, 2.5 GHz compared with 1.9 GHz. The second reason is that the overwhelming majority of Android applications are only aware of one or two processor cores. Providing more processor cores does not significantly improve performance. However, there are times when a particularly intensive application fully utilises the dual core processor and then the operating system requires a little processor overhead - for example, an email arrives and the notification engine needs to kick in. For circumstances such as this, the Snapdragon 808 can rely on the cluster of Cortex-A53 cores.