Screen transitions take longer on Octoshock in 2.9.1, but IGT is representative of actual gameplay times because it excludes the transitions.
This room is 1 in-game frame longer in the new movie, because the jump is timed differently:

Why do you take the lower route here? It cost you 54 realtime frames because you have to go back and forth (causing 2 more screen transitions).

3 in-game frames are lost due to the new timesave, because you start the next level facing backwards. But there's also 3 frames lost here:

During the next level IGT difference is reduced to 15 frames, hard to tell why, because the strats look identical?
On this screen the improvement is reduced to just 2 IGT frames:

2 IGT frames are gained back before the next level starts. During the rest of the game the difference becomes 11 IGT frames of overall improvement.