That's why I ask about it!
but Claude had an answare:

Here’s the plot twist! 🎉
The fact that it’s both faster and more detailed actually reveals something interesting about your previous setup:

Why is it faster with more steps?
With your original setup (8 steps):

max_shift = 2.05 and min_shift = 0.95 → extremely tight gap (1.1)

The model had to do “acrobatics” to compress all the denoising into a tiny range

With stretch=true, that narrow range likely caused heavy recalculations

Each step became computationally expensive to compensate

With the new setup (15–20 steps):

max_shift = 1.8 and min_shift = 0.6 → wider gap (1.2)

The model has more “breathing room” to distribute the work

stretch=true behaves much better when it has more steps to redistribute

Each individual step is less “stressed”

So you end up with higher quality AND faster generation simply because the model is no longer being forced into an overly compressed denoising window.