I have noticed that when using last uboot in linux-sunxi repository the A13 MICRO has a performance regression.
I do usually test the board with guvcview for days. This evening I installed uboot following instructions bellow and noticed that the video was very slow comparing with uboot in Preliminary debian image at https://www.olimex.com/wiki/A13-OLinuXino-MICRO (https://www.olimex.com/wiki/A13-OLinuXino-MICRO), so at last I decided to extract the uboot from the mentioned image to create my own images.
The slowdown can be also easily noticed when loading lxde desktop.
git glone https://github.com/linux-sunxi/u-boot-sunxi.git
git checkout origin/sunxi-current -b tmp
make A13-OLinuXinoM CROSS_COMPILE=arm-linux-gnueabi- -j 5
dd if=spl/sunxi-spl.bin of=/dev/sdd bs=1024 seek=8
dd if=u-boot of=/dev/sdd bs=1024 seek=32