One of the key properties of PhotoLab is to apply a preset to all the images that are in the selected folder. Let me explain.
PL cannot “not apply a preset”:
Even if the default preset is set to “No Correction”, PL calculates previews from RAW data of all those images in the selected folder. The original, built-in preview is only shown before PL replaces it with its own preview.
→ The least that PhotoLab can do is, to apply the “No Correction” preset.
All images of the selected folder:
The more images are in the selected folder, the more time and resources PL will take to create its own previews of these files. Therefore, and that is something like an agreed best practice, it’s best to
→ keep the number of images per folder in the low hundreds max.
It’s of no use to wonder why DxO has implemented PL like this. The answer will always be that they did what they did. And although DxO reads posts here, there has been no sign yet to release that “always-on” handbrake, e.g. with a setting that prevents PL from calculating previews before it is asked by the user to do so or before an image is actually selected.