I only watched the first episode of Knights of Sidonia, and the main reason I dropped it was that the CG ran at an unbearably low framerate. I just took another look at it, and it looks like most of it past the opening sequence was "on threes".
I can understand why it's rare for anime to do hand-drawn animation (besides pans/etc) on ones - it takes a lot of work!
But I can't comprehend why this would happen with Sidonia - it was 100% CG! It seems like cranking the framerate up to twos or ones would just be a matter of changing a setting in whatever tool they were using to render the CG. Last year's "Aoki Hagane no Arpeggio" was full-CG too, and it didn't have this problem...
Do we know why the CG framerate was so low? Was it production issues, or an artistic choice, or...? (Side question: did it get better in later episodes and/or on the BD?)