I have put my hands on a Raspberry PI 2, and I have found that it takes 6 minutes to compile the backend code using the 4 cores of the ARMv7 processor, and close to 20 minutes on a single core (without ccache). The test has been done using ArchLinux ARM with a micro SD card of class 10 (said to be able to manage 50MB/s in write, 60MB/s in read). In comparison, the buildfarm machine hamster, which is a Rasp PI 1, takes close to 2 hours to do the same operation, using the same OS and a similar class 10 card (30MB/s but the I/O is not the bottleneck).
Thanks for sharing this info. I'm looking forward to getting my hands on an rpi2 soon for some of my other projects. Having an idea of the increased performance, especially related to compilation, was certainly something I was curious about.
