Here's the deal
I've got 25 fps (shoot in) footage on 25 fps timeline.
When i'm increase clip speed by, for example, 10% or 20% (no matter) it results choppy playback, feels like some frames being dropped.
All 3 increasing clip speed methods:
conforming (interpret footage)
Results the same choppy playback
It is not a hardware problem, seems like i just don't know something special.