Partitions created by live cd are offsized - causing very low performance.
I verified active bugs and did not find anything similar, so I created a bug.
I gave High priority because modification of already created partition scheme is very problematic after go live.
Two different tools (Debian Installer and SystemRescueCd 3.5.0 notified the same problem:
Partitions created by oi 151 a7 live cd are offsized by some kilobytes usually (starting sector in wrong point).
I was informed that this may result in very poor performance.
I verified it and unfortunately I have to confirm it:
1). My /dev/sdc4 partition encription took 5 hours and started at 75 MB/s and finished at 62 MB/s.
2). After recreating this partition - with start block in correct point by Debian Installer
i verified that encryption in System Rescue Cd took 4 hours - started at 90 MB/s and finished 65 MB/s.
Thank you in advance and best regards - Piotrek - pe3no.