Image scaling performance

[Michael Zimmermann]

Any ideas what could slow down the image scaling algorithm?
The only reasons I could think of would either be slow memory or some
compiler problems. Since my Ram is mapped cachable I don't think the
RAM is too slow.

I even forces using the Nearest neighbor algorithm already. It speeds
things up a lot but it's not as fast as you'd expect.

Some technical info:
ARMv7
Linaro GCC 4.9
MMU setup is done by the previous bootloader(I disabled GRUB's (uboot)
MMU setup - it prooved to be faster)