So you want to "discard" pictures that are
not used for reference. But you still want to display these pictures
How do you want to display a picture that has been discarded ???
As said in my previous post: I believe the only the thing you can do is skipping the deblocking on non-referenced frames, but
not discard those frames entirely!
Furthermore I think skipping the deblocking on non-referenced frames won't give that much speed-up. The only frames that aren't referenced are b-frames.
And even that is only the case with b-pyramid disabled. With b-pyramid b-frames may be referenced by other b-frames as well.
Last but not least deblocking is not the most compute-intensive task. CABAC decoding is, given that CABAC is used...