This article has pictures of gnome-disks benchmarks that was run on a GT-I9300 under Parabola with the Replicant 11 kernel and u-boot with the nonfree BL1.
Xorg had instabilities so I had to take pictures before the display went black and/or were corrupted.
This information might be interesting if you want to know if it's better to run an OS on the eMMC or MicroSD (for instance if you want to do tests and need to reboot often or want to compile on the device).
Here we can see that the read speeds are between 70 and 80 MiB/s in average