Because it is an ESM file loaded early in the sequence, the fixes it implements become a foundation for all other mods. When PRP.esp later rebuilds the previs data, it does so by reading and respecting all the corrections already made by PPF.esm. This is why the load order is so critical: the fixes in PPF.esm must be established before the repair work in PRP.esp is performed.

By understanding that Ppf.esm is a locally generated Previsibines pack from the Place Everywhere mod, you can confidently remove, regenerate, or bypass it. Use xEdit to strip the master file requirement from problematic plugins, or create a dummy file if you need a quick fix.

The game groups thousands of static objects (walls, trash, buildings) into a single mesh to reduce draw calls on your CPU.