[Cin] Playback slowdown

[Andrea paz]

I did some tests again with the 2019/01/16 release and I don't notice
any more slowdown problems with the playback.. Where before I went
from 30 fps to 10 or even 1 fps; now I go from 30 to 27 - 28 fps.
I'd say the problem is solved! Thank you very much.
In my opinion, the mismanagement of mkvs and pngs remains; but no more
than it always has been. Do you think it is better to open an issue on
this subject?