So you're addicted to Skyrim, and you're addicted to using mods...

You have a mod list that is running 100 deep, but you are starting to experience undesirable performance from the game: random CTD's, unexpected mod behavior, broken quests, etc.

This guide will help beginner and intermediate mod users alike. There are a few basics you should understand about how mods work and how the Creation Game Engine handles those mod files.


First of all, think of Skyrim's Creation Engine like a high performance race car engine. Both have tons of "moving parts" and even the slightest misaligned gear or misfiring sparkplug will degrade your performance rapidly, if not bring the whole thing to a crashing halt. Also, like a racing engine, it needs to be maintained and kept "clean" on a regular basis. You can't expect to drive a top fuel race car continuously without going through very regular maintenance check-ups and tweaks.

Skyrim's engine is a delicate beast. If treated properly, it has the capability of producing some pretty brutal performance, and with the proper tweaks and mods, it can output a performance index that is much greater than Bethesda ever intended.

All of this comes at a price. You should never expect to simply 'drop in' a bunch of mods and expect it all to work out of the box. Most of the time it will (especially if the mods are fairly simple), but you should always understand why or why not.


Since you are here on this mod's page, you are probably ready to graduate to installing more complex mods whether you know it or not (or maybe you already have, but still want to learn more about how mods can work together). Here are a few tips to keep in mind:


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1. READ the Mod description - I cannot stress this enough. ALWAYS read through the entire mod description so you get a feel for exactly what the mod does, as well as known issues/conflicts, FAQ's, special installation/uninstall instructions, etc. Never assume just because a mod looks to be a run of the mill "armor mod" that all you do is drop it into NMM and expect to craft it at the nearest forge or whatever.


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2. Browse the contents of the mod - Even if you use automatic download with NMM, i strongly suggest you also download manually and open the contents to see whats exactly under the hood. The mod files may not make much sense to to beginners but at least familiarize yourself with what components the mod is actually installing. Some things to especially consider are:

- Scripts. Some mods may install a few to a ****-ton of scripts. The quantity of scripts is generally not an issue (skyrim itself has about 10,000 script files), it is more about script syntax and quality of how they are written etc. Now, I don't expect you to be able to open them up and understand exactly what the scripts do, but just keep in mind if there are scripts or not (because this can often factor in to troubleshooting mods, especially based on patch version number, since many script functions require minimum patch specs)

- File size. Open and browse through the texture files, check to see just how many .dds files are very large. If you have a ton of .dds files that are all like 10mb or larger, make sure your system can handle it. Using too many high res textures will drop your FPS and sometimes CTD unexpectedly. Luckily, the game will only parse the textures it needs at any given time. So, even if the mod's total texture folder size is like 500mb, the game itself will not load all of those simultaneously in memory.


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3. SAVE GAMES - This is probably the single most significant factor in performance health. You need to understand exactly what is written into a save game. Since this is a pretty complex subject, I will go more into detail later. For now, here are a few things you should be doing to reduce the risk of save game corruption.

- SAVE OFTEN. You should have a continuous save game rotation of at least 20 save files deep. This means, always have 19 additional save points at any given time in case you need to load a previous save to undo something that may have gone wrong in your most current save. What I do is save sequentially, and when i hit the 20th save, i overwrite the first one i made, and continue overwriting in sequence. That way, I will always have 19 backups, but not clutter my save folder with hundreds of old saves.

- Make "Landmark" saves. You should always have a handful of important "landmark" saves that never get overwritten, except when reaching a landmark of the same type. For example, I have my first landmark save which has NO MODS installed, directly outside Helgen after completing the initial quest. This save is my fallback to test for save game corruption when comparing to current saves (COC from main menu can also satisfy this purpose, but loading the cleanest save is always the best choice). If i suspect my current save is messed up, i will load this Helgen save to test if the conditions still apply on this save game (if it dows, that means a mod is actively screwing up the game, and not necessarily the cause of the save game data itself). Some other landmark saves would be BEFORE installing a new mod, make a temporary landmark save, so that you always have a return point to load if you don't like the mod.

- Uninstalling mods vs your save game. If you do uninstall a mod, you should try to load the landmark from before having that mod installed. If you progressed in the game too far since then for that to be an option, you need to decide whether the risk is worth it or not. Most of the time, if the uninstall was successfully followed, it shouldn't be an issue. However, there are some things that are PERMANENT even after uninstalling a mod. Scripts, player base stats (such as health, stamina etc), NPC base outfits, Perks (if the mod changed vanilla perks), etc. If a mod makes changes to any of these permanent values, it NEEDS to have a proper uninstall procedure or else you run the very likely risk of corrupting your save to the point of it being unsalvageable. If a mod adds a significant amount of scripts, it also needs a specific uninstall procedure where you need to leave modified inert versions of the scripts in your scripts folder for as long as you continue using your save game. Unfortunately Skyrim's Papyrus scripting engine cannot clean up after itself, so once you install a mod's script, the save game will look for that script.... forever, even after you completely uninstalled the mod. If it cannot find the script, it will dump a handful of errors for each missing script. To illustrate this point, I installed Dawngaurd, then uninstalled after playing for 5 minutes. After deleting dawnguard's BSA, there were over 4000 script errors because it was looking for so many missing scripts. Sometimes these errors can be harmless, but if they compound and stack, they will eventually choke the script engine and rob resources from existing running scripts.

- Monitor save game file bloat. If after you install a new mod, you notice your file size skyrocketting, STOP using the mod immediately. Report the issue to the mod author so that they can implement a fix if possible. The biggest causes of file bloat are: poorly written scripts which use a continuous "unchecked" update loop (i call these "dirty" or "leaking" or "feral" scripts), scripts which do not clean up after themselves (like using placeAtMe to drop an items continuously, but never actually deleting that object eventually - those objects remain in the world and your save game data forever, and will continue to populate increasingly). In all fairness, even some of the vanilla Bethesda scripts have these errors.


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4. LOAD ORDER. Load order is basically the order in which the game will load masters (esm) and plugins (esp). Masters will always load before plugins. If you have multiple plugins that override the same record, the last loaded plugin will take affect. The game will completely ignore previous changes to that record, and not "combine" both changes. In this way, load order plays a significant role in performance and compatibility, because a mod with a higher load order that overrides a record from a mod below it, can actually "break" that mod if the mod's functionality relies on the behavior of the change it applies. I strongly suggest using a tool such as BOSS to maintain your mod list load order.

- Esm vs Esp. As a mod user, there may not be a whole lot you need to know about the difference between esm and esp files, other than the load order restrictions of esms. It should also be noted that there are sometimes inexplicable conflicts that arise from multiple esm files. This can happen with or without mods installed. Dawnguard esm and Update esm can sometimes conflict with itself, as seen even on an Xbox with obviously no mods installed. Often, this esm conflict will cause large static landscape objects to completely disappear from the world. The cause of this is unknown, and can appear even long after either or both esms are installed. This happens a lot with housing mods, since a lot of those use esm files. Sometimes load order of the esms may help reduce this strange glitch, even if none of the esm records overlap (just "one of those things").


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5. STAY CURRENT. You should always try to stay on top of latest versions, both mods and the game itself. Understandably, some users may not want to install the latest game patch due to new bugs sometimes being introduced. If you do decide to stick with an older patch version, you should always check with the mod to see if you meet the minimum patch requirement. Patch versions can include significant changes to the game that will not be recognized if the mod and game patch are out of sync.

- Make sure you are on top of current versions of your mods. It isn't uncommon for a major patch change to break an existing mod. If it looks like the mod is no longer being updated, you will likely have to revert your game to an older patch or uninstall the mod if the performance is being affected. It's a balancing game, and you need to stay on top of it.

- Avoid using ancient esp plugins and especially esms. If you have a mod from before Feb 7 that uses an esp or esm, and you are running a patch that is 1.4 or higher, you should stop using those old files and upgrade to a newer version if possible, or just uninstall them. Those old esp files were created using an outdated tool called TesSnip, which was designed for Fallout (to this day there is no version of TesSnip or TesVsnip that is safe to use for Skyrim's current definitions). With all the new record definitions in Skyrim and its iterative patches, those old definitions found in the esp files will likely cause corruption eventually.


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6. Accept the inevitability. It is ultimately inevitable that some mods simply can never work with one another. Usually, you can tell by the mod's description and what it does - if you already have another mod that does the same thing or similar, it will probably conflict at some point. As a sort of 'rule of thumb', you may want to avoid using too many mods that make unnecessary broad vanilla changes (unless the point of that mod is to be an 'overhaul'). If it is an overhaul mod, it is generally a good idea to only have one overhaul mod of any given type (such as lighting/weather, perks, vampirism, followers, spouses etc.)



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TROUBLESHOOTING

Even after following this guide, and even if you are an experienced mod user, you will eventually run into a problem with mods or unexptected save game corruption. There are a few basic troubleshooting tips you should always try first.

- If you have installed a new mod correctly, followed all the directions, and it seems like everything should work with no conflicts etc. but you still have problems with the mod, check the comments section on the mod page to see if anyone else is having the same issue. If you find that this is a common problem, there may be something wrong with the mod itself (or by coincidence most problems being reported are caused by the same issue - which is very plausible).

- You can run a few basic tests to see if there is a problem with your save game or a mod conflict. To test for save game problems, try quitting to the main menu and open the console (don't load any save game. Type: COC Riverwood into the console. Or, if you have been using my suggestion to create a clean landmark, load your 'virgin' Helgen save (which would be better than a COC). After the game loads, check to see if the mod in question is working properly. If the mod works fine in this test, it means there is a problem in your current game save data. If it is still broken, you can try testing for mod conflicts.

- Testing mod conflicts is a very tedious process. You can start by disabling mods one at a time (starting with the ones you suspect are causing problems first). Always load your clean save or continue with the COC from main menu when running the mod conflict test. If you narrow down a problem mod, try loading your current save game with that mod disabled. If everything works, you can decide to uninstall the problem mod, or try moving its load order down to see if they will play nice together. If the problem mod refuses to cooperate, it needs to be uninstalled. If after disabling the problem mod, your clean game save works, but your current save game does not, it means that the mod needs an uninstall procedure. If the mod author did not prove you with one, it can be almost impossible to determine how to uninstall the mod without a strong knowledge of how the mod works internally. I would suggest PM'ing the mod author for a proper uninstall procedure. If a mod author still refuses to provide one, it is probably a good idea to never use any mods from that author (this is generally rare, most authors are willing to help). If nothing works, you may have to start a new game.