@G0MJW: yes, that's exactly what happens.
@R0AU: If LDPC takes too long, maybe you've chosen the wrong modcode from the list. Also, weak signals mean more CPU load for LDPC decoding.
Next version won't have the list, because it's coded inside the DVB-S2 frame anyway. I'll also implement multithreading for the LDPC decoder, so it will benefit from multiple CPU cores.