Fallout 4

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About this mod

Full rebuild of precombined meshes and occlusion (previs) information for Fallout 4, reducing draw calls everywhere, which depending on location, should increase frames per second compared to the vanilla game, and also includes any relevant bug fixes I can find and fix not already handled by UF4OP. Requires Season Pass / All main DLC.

Permissions and credits

This is a PSA intended for the steam discussion forum userbase. This mod is incompatible with the Frost mods. Go here instead for a suitable replacement.

aka: The Unofficial Fallout 4 Precombines Patch

[ PRP-Stable | PRP-Unstable | PRP-SS2 | PRP-Vault120 | PRP-XB1 ]

If you are here following the BitRaitRec guide PDF, you want the package in main files instead of what the document tells you, as PRP no longer has split packages. (Historically before 0.49, PRP came in Ext and Int packs.)

This mod assumes your DLC .esm files are pristine and uncleaned, please restore them if you have previously autocleaned them, as there's small differences in record formats that xEdit does not account for when rewriting the master files on save, this might cause unexpected behavior.

Current direct contributors:
krrptd, Glitchfinder, VlitS, feeddanoob, VishVadeva, CyberDanz, ... [if you've contributed here and want named, please let me know, I'm going off memory here]

Included mods with first versions implemented:
Collision Fixes from Scrap Everything (0.55), Flicker Fixer (0.57), Airport Transparency Fix (0.58), Far Harbor - Cliffs Edge Hotel Wall Rest Ring Lower Fixed (0.58), Cliff's Edge Hotel Window Fix (0.58), Glitch's Fixes (0.58), Vault 111 Floor Guide Fix (0.58), Technically any mod that adds Max Height records to Nuka World, but we freshly generate it. (0.57), Collision and Mesh updates from Exoclyps as part of the Storywealth Collective patch (0.60), Underwater Glass Fix (0.64)

Current Translator credits:
Spanish (Spain): kittyowilder, Italian: samyesu, Brazilian Portuguese: Rikintosh2, French: Oaristys and their team, Japanese: Anonymous users from 2game, Polish: Someone from the support discord that I don't know the nexus user ID of, Simplified Chinese: Vozhuo, Russian: Slimer91 (before 2.1.5), Djezendopus (2.1.5), German: SkyHorizon3, any other languages not listed here are currently unsupported, contributions welcome!

Constantly updated changelog/bugtracker: Here.
Primary Support Discord (Collective Modding): Here.

Please see the sticky post in comments for more recent information than what's below, and pardon the dust.


PRP started out as an attempt to replace the aging and technically broken (the user base patched around it's flaws) Fo4FI_FPS_Fix which it itself was a replacement of Boston FPS Fix, both mods originally attempts to update the information provided to the precombine and previsual system in first the general Boston area (thus the name), and then the entire Commonwealth (the other mod) to improve performance and restore it in some cases where it was previously broken through official patches. For my mod, I historically did it all cell by cell in the Creation Kit the old fashioned way, up till 0.49 was created when several fine people were already figuring out the internals of the Creation Kit and how to set up the hidden command line mode of generation for the system itself. I did some independent testing at first and eventually caught wind of several discord servers that have given me countless advice and assistance in construction of the mod itself. This mod would not have been what it is today without the help of the community.

Special shout outs to ShadowOfTheWind (setting me straight at the beginning regarding visibility generation), VlitS, Searge, Evan, yarrmateys (Various assists and improvements via tools and technical assistance with issues that had came up in the mod's development), CyberDanz, ScreamingLake, Marvesly, MasterLix, and various others in the support discords for so much help and support with QA, feeddanoob, Hap, Poet, krrptd for compat patch development or in the case of Frost, replacement and additional contributed bugfixes. Arthmoor for the obscure history lesson pulled from their bug tracker and the rare piece of advice. Also countless others that have reported bugs and helped out with user support issues that for the life of me, I cannot fit in the mod description.

Though the mod does technically depreciate both of the above mods, I never intended to obsolete BostonFPSFix, as it does have a use in cases where you don't want to have so much of a compatibility window compared to mine. The original mod author is more than welcome to take the accumulated bugfixes and rebuild their mod with them in mind if they apply when they return to active modding.

Ever since 0.51 hit, I've take it upon myself to more or less try and fix what I can in the purview of what the mod touches, and as a result became an extension of the UF4OP itself by virtue of what I do, even submitting bugs myself to their tracker when it's something that either they can fix or I've already fixed and is under their purview. The entire list of changes pending and current lives at this page of the git repository I use for mod development: PRP-Bugtracker. For submitting bugs, I prefer posts with detailed information about the problem or being notified in multiple modding discords that most of the user base are likely already inside of. The primary one is at the Collective Modding discord, though I do frequent the Black Pearl, MOFAM, xEdit, Frost, Horizon, The Midnight Ride, among other obscure discords. If you frequent a certain lesser known but still used imageboard, use the Previsibines term when talking about bugs so I can search for it in the post archives easier.


PRP at it's core is an entire rebuild of the game's previsibines file set. (VlitS coined the term, it's a portmanteau of Precombines and Previsual or Umbra information.) As the mod is built against UF4OP, it absolutely requires all six mainline pieces of DLC (everything in the Season Pass except for the HD Resolution pack, which most people don't install anyway for various reasons, and I'm not giving you another one.), and thus will not change. If this bothers you, wait for a steam sale or check other places for a steam key. The information is built against the latest steam release in an automated fashion, and thus will likely never be bug free. For most people, you download the current stable release, the expected version is below the logo at the start of the description. Install that like any other mod, as it's self contained, preferably through Mod Organizer 2, but Vortex users have reported success and LOOT does recognize all mods posted on this page.

Due to the nature of the files included, there will always be issues, most of which culminate in a pair of know types of problems that are usually solved by fixing your load order.

Since 0.57, the mod includes a FOMOD and enough compatibility to be manually installed with the Wyre Bash Installers tab if the fomod converter isn't sufficient to deal with it. For most people, PPF+PRP by itself is fine, but if you have any of a small set of mods, patches are included for compatibility. LOOT's masterlist is aware of PRP's plugin set and will get your load order with respect to the mod sorted out. Don't trust it completely for every load order, though.

Common Questions and Answers

Check the pinned in the mod's comments first before reading this, as it's usually up to date with what's going on.

Q: I use FROST, do I need PRP?
A: Negative. krrptd and the Frost community maintain an equivalent to PRP that includes some of my fixes (it would be all of them, but the dev has a family to take care of, and I can understand mod dev time being limited.), which can be found here, recently remade as an all in one package in the same style as PRP! If you have questions, peruse their support discord or mod pages.

Q: I use Horizon, I've heard something about incompatibility?
A: Only with Enhanced Settlements, it's a known issue, hopefully to be resolved in 1.9. The CK crashes due to missing models. A compat patch is in the works for 1.8, but it'll have settlement cells with previs disabled. This is intended due to the way mod functionality is implemented, and the amount of time required to fix it would be not worth it, as 1.9 will have released by that point.
022823 Update: Tried to build against the recent 1.9 alpha builds, the plugin or some of the meshes have build quality issues that crash the CK. The full version of PRP is still incompat at this time until I can get this resolved. Use the Lite version instead. (PRP-XB1 link above)

Q: The mod I want patched isn't available on your mod page.
A: I'm aware of four others currently maintaining compatibility patches, with another currently only supporting an older PRP build. I can only personally vouch for Feeddanoob's UPPC (as of this update only compatible with 0.53, known issue), TheSoundofSnow (Poet)'s OPC, and Hap's work.
Mith077's recent works are solid but you should still notify them of any bugs you find. Anyone else making compatibility patches should target the current stable version for best results.

Q: You mentioned CRP. Is it compatible?
A: CRP come with their own precombines, though they are older in style. They are not compatible with modern PRP builds. I would have to rebuild the previs from scratch, and that's not worth it currently until Overgrowth is finished.

Q: Any other mods you know that are compatible?
A: Pfff, I wish. Generally you'll know if the description mentions PRP or Previsibines (or Previs Repair if older) in the description. I do have a laundry list of patches that need to be made, but it's better if more people do so, you know so I can continue development!

Q: This git repository you mention, does it have documentation on how you are accomplishing this voodoo that you do?
A: Right here. Pull requests welcome.

Q: Any advice on texture compatibility?
A: All texture mods should be perfectly compatible, we don't change any file name assignments in the meshes unless they are to fix specific bugs or add new entries and they are provided in PPF's .ba2 files. As of the current build, there's only one new material swap that currently exists that's included with the mod and I think only has a 4K upscale on Luxor's main texture page as a replacer for those who use it, if new texture records or such get added, they'll be shoved into PPF's archives and noted on the changelog as usual.

Q: Arthmoor is icky or I hate the UF4OP team for some reason that's stupid. Make a version without it!
A: I actively work with Arthmoor at this point and we coordinate where required, though I am just a contributor to the project, I am not part of their team. The bugtracker is my friend, not my enemy. If you are dead set on not using it, the original Boston FPS Fix still doesn't have it as a master.

Q: Can I ESL the mod?
A: Under the presumption I remember to keep the new record count below the requirement, you should be able to safely flag it for I think all of the mods on this page. PRP releases 54 or newer should have it flagged already. It's a regression or I forgot if it's not and should be reported as a bug.

Q: Geez, this question list is getting kind of long. Uhhhh, what is a man?
A: Semi-random youtube link to be funny. I don't own that video.

Q: Wait, hold up, the tutorial videos from Trosski and RedRocketTV don't match the information in the command line manual. What do I need to do?
A: Follow their guides for the GUI, except skip the first visibility generation (only do Precombined Visibility).

Q: Clean? Filtered?
A: Explained in the manual. Short version: Filtered is Creation Kit GUI (full size) and Clean is DLC and Base Game style (shared geometry which makes them much smaller, it's what PRP uses.)

Q: Console version?
A: Unless I somehow magically reduce the archive size considerably (It's 2.1GB on average), no way in it's full size. There's a cut down version available these days for specific clusters, though, click PRP-XB1 towards the top.

Q: There's been posts in the SS2 Forums about incompatibility with PRP. Is this true?
A: As of 2.0.1, at least as far as I'm aware, the two mods do not touch each other's records without the dedicated PRP-SS2 patch which only rebuilds certain interiors in the mod to be in the same style as PRP itself and does not touch the exteriors at all for conflict reasons. If anything would conflict WITH that patch, only missed UF4OP forwards and a specific cell header to push missing precombine headers forward.

Q: You have Delta updates on your mod page, what are those for?
A: Those are xdelta3 based file update packages designed to be used if you have previous supported versions of the mod to save on bandwidth and download times. Unpack the archive to your mod folder in MO2 or Vortex, make sure you have the executable present as I don't package it with the update packs if it's not already present in your system's path and run modupdater.bat.
These are no longer being issued since 0.65 due to changes in packaging that would make the resulting .ba2 file patch generation so large that it would not even be worth the time.

Q: I use Fallout 4 VR, is PRP compatible with it?
A: The VR version of the game does not support the full ESL record space that the 'pancake' or Flat version does. Since PRP's main plugins have new records, they get assigned to the first numerical records. On engines that don't support the 1.0 plugin format (Skyrim also has this limitation), a ESL record is hardcoded, which is the cause of the recent crashing. (eg: new record 000007 overwrites the player record in the Fallout4.esm) An alternate plugin set specifically for this build of the game is in the FOMOD in branch 65, and steps were taken to make sure the new records fit the above in branch 69 to make patches more compatible. Please let me know if it helps at all, as I have no way to test them.

Q: I don't see a mod that has a compat patch or a bigger patch, can I do this myself and help out?
A: Read the manual, get the Creation Kit, join the discord, ask around. I'd be more than willing to help people learn how to do this so I don't have to build the patches myself and can actually do mod work!

Q: I have Creation Club content, does PRP support it in any way?
A: Pfff, no. I'm not made of money. If you want specific CC content supported by PRP, one would have to donate a specified amount of CC currency so I can pay for it, and that can be arranged in private. I will not resort to piracy for this, as the pirated content may not be pristine or up to date.
Edited 050223: I don't support CC specifically with the mod, but I have a selection of CC that is in my test modlist (monthly free CC drops, check the shop, it's typically on a rotation or so). It's the stuff that edit or deletes vanilla object reference entries (buildings, meshes in the worldspace, that sort of thing) that are precombined that would cause compatibility issues. Stuff like weapon and armor skins would be safe for example with PRP, or if the CC item ADDS stuff specifically to an area. Until Bethseda pulls a "Anniversary" Edition gambit like Skyrim, I'm not going to consider any of them in building for the project. Only the season pass DLC is required to use PRP in addition to the base game.

Q: What happened to the patch for Aloot's Home Plate?
A: The current caretaker has included my patch for the english version (2.3). Translators should update accordingly. Existing translations are already in the repository for those that contributed them and should just reupload or recreate the translation mod page at this point.

Q: The Scrap Everything patch?
A: It's useable but it's standalone and so old it's not funny. Better alternatives exist.

Q: What happened to Flicker Fixer?
A: It got removed in 65 and later due to missing or trashed collision and geometry information in certain meshes, likely as a result of tool issues used in 'fixing' the issues. It'll be readded if and when that ever gets fixed.