[George Livingstone]

For the sake of Google, this can be one reason for Timewarp stutter: (I very rarely use Timewarp and keep forgetting about how this works myself when I do):

In my example, I wanted to play a 15fps clip at 25% speed, but then played back 4x as fast (60fps) to make up for it. ie. this just creates interpolated frames, but keeps the apparent playback speed the same.

So I set the composition to 60fps, and dropped the 15fps clip in it. If you now try to Timewarp it to 25% it will stutter. This is because the 15fps clip is still playing back at 15fps – so in the 60fps comp it plays a frame, and then repeats it for another 3! That’s what Timewarp gets, so it assumes the movement regularly stops = regular stutter.

The solution is to Interpret the clip to 60fps first (so no frames are repeated in the 60fps comp).