Simulation Flow Unleashed: A Reworked Simulation Lag Fix

When I play The Sims 4, I often notice situations that are frustrating: after a Sim finishes one action, they may remain in place for a while before starting the next one. In more populated settings, several Sims may repeatedly compete for the same object, fail, and then try again. Sometimes food, trash, or other objects are also left behind before the related action is finished.

I cannot say that all of these situations have the same cause, but they made me pay more attention to how the game handles autonomy and how mods such as Simulation Lag Fix attempt to address simulation lag.

Simulation Flow Unleashed is a version I created after studying and modifying Simulation Lag Fix. Based on my own experience playing the game, I revisited some of the original mod's timing behavior and added adjustable settings. My goal is simple: to see whether these changes can reduce situations in which a Sim is slow to start the next action, actions repeatedly fail in crowded situations, or objects are left behind before an action is complete.

Simulation Flow Unleashed is not intended to replace existing versions of Simulation Lag Fix; it is simply another option with a different set of adjustments, so players can choose what best fits their game.

The accompanying package contains additional adjustments to autonomy scoring, delays, and competition between actions. They are not required for the script mod to work; they are changes I considered potentially helpful based on my own play and testing.

⚙️ WHY MODIFY SIMULATION LAG FIX?
The Sims 4 update released on July 21, 2026 expanded Memory Boost to all platforms. According to the official announcement, this feature improves memory management, with the goals of reducing lag and improving frame rates and responsiveness, as well as reducing memory-related problems during longer play sessions.
I began using Memory Boost as soon as it became available during its early experimental period. At the time, I noticed that loading felt faster and that the game felt less prone to stuttering.
However, although I noticed some improvement in Sim autonomy with this feature, I did not feel that it was enough. I therefore continued using community mods commonly used for this issue, including Simulation Lag Fix. I later noticed that many of the original mod's settings reflected trade-offs made when hardware and engine resources were more limited. This led me to reconsider some of its more conservative limits and make several adjustments based on my experience testing Memory Boost.

EA update notes:
https://www.ea.com/games/the-sims/the-sims-4/news/update-7-21-2026

1. NO LONGER FORCE THE TIME SLICE TO 17MS
The original Simulation Lag Fix used the following setting:
time_service.TimeService.MAX_TIME_SLICE_MILLISECONDS = 17
This fixed the game's time-slice limit at 17ms. Such a limit can help control the duration of a single update and reduce the chance that the main process will affect visual updates by running for too long, but it may also divide some autonomy work into overly short portions.
Simulation Flow Unleashed no longer forcibly overrides this setting. In my test environment, the game's original time-slice limit is 33ms. After using this setting for an extended period, I observed fewer cases that may be related to very short time slices, such as Sims leaving before an action was fully completed, objects being left on tables, or some objects failing to complete their follow-up processing.
These situations may not all be caused by the time slice, but they occurred less often in my testing after the limit was relaxed.

2. ALLOW PLAYERS TO ADJUST THE THRESHOLD FOR RUNNING THE AUTONOMY TIMELINE
The original code was designed as follows:
time3 = time.monotonic()
original(self, time_slice)
time4 = time.monotonic()
if (time4 - time3) < 0.017
Simulation Flow Unleashed makes this threshold adjustable through a configuration file, with a default value of 21ms. This value is not the time limit of the autonomy timeline itself. Instead, it determines whether the autonomy timeline is allowed to run after the main update has finished.
A lower threshold makes the mod more conservative, while a higher threshold allows the autonomy timeline to run more often. The most suitable value may vary depending on hardware, save-file contents, and other installed mods.
Please keep the .cfg configuration file and the .ts4script script file in the same folder. Both files are required; do not delete either one.

3. ADJUST THE PENALTY CURVE USED WHEN AUTONOMOUS ACTIONS COMPETE
One of the more important adjustments in the accompanying package is the FULL_AUTONOMY_ATTENTION_COST curve in the autonomy.autonomy_modes tuning.
In the original curve, the score drops very quickly in some highly competitive ranges, causing certain autonomous options to lose almost all of their score instead of becoming gradually less attractive. When the system cannot find a sufficiently good alternative, this may lead to a Sim standing idle rather than trying an option with a slightly lower score.
I adjusted the curve so that the penalty decreases more gradually in highly competitive ranges. This does not make every option easier to select; it reduces sudden score collapses and gives the system more opportunity to try a second-best option.
In my testing, Sims stood idle for long periods less often in more populated situations. However, this adjustment cannot completely resolve every problem involving competition between autonomous actions.

4. OTHER AUTONOMY-RELATED XML ADJUSTMENTS
The accompanying XML files also include several adjustments related to autonomy delays and competition:
* Increasing the delay when there is no primary interaction (Primary SI), to prevent the game from retrying immediately too often.
* Increasing LOCKOUT_TIME from 15 seconds to 18 seconds, reducing the chance that the same autonomy situation will repeatedly compete again within a short period.
* Adjusting SUBACTION_GROUP_WEIGHTING so that the relative weights of general subactions and idle actions are closer to each other.
* Adjusting the randomization settings for some autonomy motives.

These adjustments do not create or drive a separate autonomy timeline, and they do not directly change Simulation Flow Unleashed's scheduling mechanism. They are intended to improve the selection, retry, and competition behavior of autonomous actions; the actual effect may vary depending on the game situation.

⚠️ KNOWN LIMITATIONS
To be clear, these adjustments are not a universal solution. The following issues are still present in my testing:
1. In high-density social situations such as large parties, multiple Sims may still repeatedly fail while competing for the same popular object, such as the only stereo at a party.
2. Some third-party mods may contain their own logic problems, such as incorrect target selection for a particular interaction. Those issues are outside the scope of these adjustments and should be reported to the relevant mod author.
3. Testing so far has focused mainly on small and medium-sized households and some large community lots. It has not covered every possible game situation, and the results may vary depending on each player's mod configuration and hardware.

🔧 COMPATIBILITY
1. Because this mod is based on Simulation Lag Fix, it cannot be installed together with another version of Simulation Lag Fix. Keep only one version installed.
2. The accompanying package conflicts with Zero's Faster Social Autonomy and Tyjkor's Less Frequent Idle because they all modify the autonomy.autonomy_modes tuning.
3. In my testing, this mod worked alongside Tyjkor's Queue Guard and Turbodrive's Simulation Timeline Unclogger. Players who need them may consider testing these combinations with their own setups. These mods may help mitigate problems that can occur in The Sims 4's single-threaded simulation environment, including the object-competition issue mentioned above. The adjustments in my package can only reduce the problem, not eliminate it; in more severe situations, mods of this kind may still be useful as an additional safeguard.

🤝 ACKNOWLEDGEMENTS
1. This mod is based on the Simulation Lag Fix source code provided by Xerox. The original author of Simulation Lag Fix was simmythesim; Xerox later took over maintenance, and the version most widely used in the community today is maintained by SrslySims. Special thanks to the original author for the original concept, and to the mod authors who continued maintaining it. I did not use the earliest version myself; it was through later maintained versions of Simulation Lag Fix that I discovered how useful this mechanism could be, which led me to study it further and create this mod.
2. Thanks to Coolspear. I also used his Quicker Sim Autonomy & Simulation Lag Improvements. Although my mod does not use Coolspear's values, his work helped me understand which XML settings could be useful when addressing Sim autonomy.

Thank you for reading, and I hope this mod is useful in your game. :)

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我在玩The Sims 4時，常注意到一些讓人困擾的情況：Sim做完一個行為後，會在原地停留一段時間才開始下一個行為；在人數較多的場景裡，幾個Sim可能反覆競爭同一個物件，失敗後又重新嘗試。有時候食物、垃圾或其他物品做到一半，也會被留在原地。
我不能確定這些現象全部都是同一個原因造成的，但它們讓我開始注意遊戲如何安排自主行為，以及像 Simulation Lag Fix 這類模組，是如何嘗試處理 simulation lag 問題的。

Simulation Flow Unleashed 是我在研究並修改 Simulation Lag Fix 後做出的版本。我是根據自己的遊玩經驗，重新檢視原模組的時間處理方式，並加入可以調整的設定。我的目標很單純：當 Sim 做完一件事後遲遲沒有接著做下一件、多人場景中行為反覆失敗，或某些物品做到一半被留在原地時，看看能不能讓這些情況少一點。

Simulation Flow Unleashed 並不是要取代現有的 Simulation Lag Fix 版本，而是提供另一種調整方向，讓玩家依自己的遊戲情況選擇適合的版本。
隨附的package則是我另外針對自主評分、等待時間與行為競爭所做的調整。它們不是腳本模組運作的必要部分，而是我在遊玩與測試過程中，認為可能有助於改善某些自主行為問題的嘗試。

⚙️ 為什麼要修改 Simulation Lag Fix 模組
2026 年7月21日的《The Sims 4》更新已將Memory Boost推廣至所有平台。官方表示，這項功能改善了遊戲的記憶體管理，目標包括降低延遲、改善幀率與反應速度，以及減少長時間遊玩時的記憶體相關問題。
Memory Boost還在早期實驗階段時，我就開始使用。當時我明顯感受到讀取速度變快，遊戲中的卡頓也有所減少。
不過，我認為Memory Boost對Sim自主性的改善仍然不夠，因此繼續使用社群中常見、用來改善這類問題的模組，其中一個就是Simulation Lag Fix。可是隨後我又注意到，原模組的許多設定，是在硬體與引擎資源較有限的前提下做出取捨，使我認為部分原本較保守的限制有重新檢視的空間。因此，我根據自己在Memory Boost測試期間的使用經驗，重新調整了 Simulation Lag Fix 的部分設定。

EA 的更新說明：
https://www.ea.com/games/the-sims/the-sims-4/news/update-7-21-2026

1. 不再強制將時間切片限制為 17ms
原版 Simulation Lag Fix 使用以下設定：
time_service.TimeService.MAX_TIME_SLICE_MILLISECONDS = 17
這一段程式會將遊戲的時間切片固定設為17ms。這種設定有助於控制單次更新時間，盡量避免主流程因單次處理過久而影響畫面更新，但也可能讓部分自主工作被切得過細。

Simulation Flow Unleashed不再強制覆寫這項設定。在我的測試環境中，遊戲原始的時間切片上限為33ms。經過長時間使用後，我觀察到這樣能減少部分過去與過短時間切片相關的行為，例如Sim沒有完成處理就離開、物品被遺留在桌面上，或部分物件未能及時完成後續流程。
這些現象不一定全部由時間切片造成，但在我的測試中，放寬時間切片後確實較少出現。

2. 讓玩家調整自主時間軸的啟動門檻
原始的程式是這樣設計的：
time3 = time.monotonic()
original(self, time_slice)
time4 = time.monotonic()
if (time4 - time3) < 0.017

Simulation Flow Unleashed 將這個門檻改為可透過設定檔調整，預設值為21ms。這個數值不是自主時間軸本身的時間上限，而是「主軸完成後，是否允許額外執行自主工作」的判斷門檻。
較低的門檻會讓模組更保守，較高的門檻則會讓自主時間軸更容易執行。實際適合的數值，可能會因硬體、存檔內容與其他模組而有所不同。
請務必將 .cfg 設定檔與 .ts4script 腳本檔放在同一個資料夾內；兩個檔案都需要保留，請勿刪除其中任何一個。

3. 調整自主評分競爭時的懲罰曲線
搭配package中較重要的調整，是 autonomy.autonomy_modes tuning裡的 FULL_AUTONOMY_ATTENTION_COST 曲線。
原始曲線在部分高競爭區間會快速下降，使某些自主選項的分數幾乎直接歸零，而不是逐步降低。這可能讓系統在找不到理想替代方案時，選擇讓Sim暫停或呆站，而不是嘗試分數稍低的其他選項。
我將這條曲線重新調整，使高競爭區間的懲罰較為平滑。這並不是讓所有選項都更容易被選取，而是減少分數突然崩落的情況，讓系統保留嘗試次佳選項的可能性。
在我的測試中，人數較多的場景裡，Sim長時間呆站的情況有減少，但這項調整不可能完全解決所有自主競爭問題。

4. 其他自主性 XML 調整
隨附的 XML 也包含幾項與自主延遲及競爭有關的調整：
* 增加沒有主要互動（Primary SI）時的等待時間，避免遊戲過於頻繁地立即重試。
* 將 LOCKOUT_TIME 從15秒調整為18秒，降低相同自主情境在短時間內反覆競爭的機會。
* 調整 SUBACTION_GROUP_WEIGHTING，讓一般子行為與待機行為的相對權重更接近。
* 調整部分自主需求的隨機化設定。
這些調整不會建立或驅動獨立的自主時間軸，也不會直接改變Simulation Flow Unleashed的排程機制。它們主要是為了改善自主選項的選擇、重試與競爭行為；實際效果仍可能依遊戲場景而有所不同。

⚠️ 目前已知的限制
坦白說，這些調整並不是萬能的，以下是目前仍然觀察到的問題：
1. 大型聚會等高密度社交場景中，仍會觀察到多個 Sim 競爭同一個熱門物件（例如派對中唯一一台音響）反覆失敗的情況。
2. 部分第三方模組本身可能存在邏輯缺陷（例如特定互動的目標判定異常），這類問題不在本文調整的範圍內，需要向該模組作者回報。
3. 以上測試主要在中小型家庭與部分大型社區場景下進行，尚未涵蓋所有遊戲情境，效果可能因個人使用的模組組合、電腦硬體而有差異。

🔧 模組相容性議題
1. 由於本模組是以Simulation Lag Fix為基礎修改，因此不能與其他Simulation Lag Fix版本同時安裝，請只保留其中一個版本。
2. 隨附package會與 Zero 的 Faster Social Autonomy 及 Tyjkor 的 Frequent Less Idle 衝突，因為它們都會修改 autonomy.autonomy_modes tuning。
3. 我在測試中確認本模組可以與Tyjkor 的Queue Guard及Turbodrive的Simulation Timeline Unclogger同時運作；有需要的玩家可以考慮依自己的遊戲情況測試是否搭配使用；這些模組可能有助於緩解《The Sims 4》單執行緒模擬環境中可能出現的問題，例如前面提到的物件競爭議題。package中的調整只能舒緩，無法完全避免；在較嚴重的情況下，這類模組或許仍能作為額外的防護。

🤝 致謝
1. 本模組基於 Xerox 提供的 Simulation Lag Fix 原始碼修改而成。Simulation Lag Fix 原作者為 simmythesim，Xerox 曾接手維護，而現行主要在社群中廣泛使用的是 SrslySims 接手維護的版本。特別感謝原作者的創見，以及後續接手維護的模組作者。我沒有使用過最早的版本；是後續維護版本讓我有機會接觸並發現這套機制的作用，之後才進一步研究，做出現在這個模組。
2. 感謝 Coolspear，我也曾經用過他的 Quicker Sim Autonomy & Simulation Lag Improvements。雖然我的模組沒有使用 Coolspear 調整的數值，但是他的作品讓我知道哪些 XML 設定可能有助於處理 Sim 的自主性。

謝謝閱讀，希望這個模組能在你的遊戲中派上一點用場。:)