Prison Architect: Best preferences.txt for Massive Prisons

The goal for Prison Architect optimization is Logical De-cluttering. When managing a “mega-prison,” the biggest “tick-hogs” are dynamic shadows, pathfinding for staff needs, and complex utility loops. This configuration focuses on disabling non-essential environmental effects and simplifying the pathfinding logic via the .txt settings and specific mutators.

Hardware Compatibility & Expectations

• The Single-Thread Limit: Prison Architect primarily utilizes only one or two CPU cores for its heavy lifting. Higher clock speeds (GHz) matter more than high core counts.
• Map Size vs. Population: A “Large” map with 500 prisoners often lags more than a “Small” map with 1,000. Land expansions significantly increase the complexity of the pathfinding grid.
• Utility Loops: Avoid “circular” pipe and wire designs. The game engine has to constantly recalculate the flow direction in loops, which can tank performance at scale.+1

File Location

The configuration file is located in your AppData folder:%USERPROFILE%\AppData\Local\Introversion\Prison Architect\preferences.txt

Best preferences.txt for Massive Prisons

Open the file with Notepad and modify these specific values. If a line doesn’t exist, you can manually add it.

# Graphics and Performance Optimization
ScreenFiltering          Multisampled      # Set to "Nearest" for a major FPS boost on low-end PCs
ScreenWindowed           true              # Windowed mode can help with multi-tasking lag
ScreenW                  1920              
ScreenH                  1080

# Simulation Optimization
PhysicsIterationCount    1                 # Reduces the frequency of complex physics collisions
ToggleShadows            false             # CRITICAL: Shadows are the biggest CPU drain at high pops
ToggleFogOfWar           false             # Disabling Fog significantly reduces visibility checks
AutosaveTimer            15                # Increase to 30 or 60 to prevent constant save-stutter

# Experimental Stability
AsynchronousJobSearch    true              # Offloads job searching to a background thread
RenderSkies              false             # Removes clouds and unnecessary background sprites

Master Tip: For prisons over 2,000 inmates, the best performance boost comes from the “Fast Walking” and “Spectral Staff” mutators. Spectral Staff allows staff to walk through walls, completely bypassing the complex A* pathfinding around doors and hallways.

Key Parameters Analysis

Parameter	Recommended Value	Impact
ToggleShadows	false	Saves massive CPU cycles used for real-time light casting.
PhysicsIteration	1	Reduces the math required for entity-to-entity collisions in crowds.
Filtering	Nearest / Multisampled	Use “Nearest” to stop the engine from blurring textures, saving GPU memory.
AutosaveTimer	30	Prevents the 5-second “freeze” that occurs when saving large files.

Strategy for Massive Populations

To maintain high TPS (Ticks Per Second) as you expand:

• The “One-Way” Pathing: Design your corridors as 3-tile wide “highways.” Bottlenecks are death for performance; when 500 prisoners try to use one door, the pathfinder enters a calculation loop that freezes the game.
• Centralized Logistics: One massive Laundry and one massive Kitchen are better for performance than many small ones, as it reduces the number of “Work Job” requests in the global queue.
• Disable Staff Needs: If your prison is already massive, staff pathfinding for their own needs is extremely inefficient. You can disable this in the save file by searching for StaffNeeds true and changing it to false.

Troubleshooting & Common Fixes

• FPS Drops During “Work” Time: This is caused by the Job Queue becoming too long. Avoid starting massive construction projects while your prisoners are also in their work regime.
• UI Flickering: This often happens in prisons with too many “Power Loops.” Break your electrical grid into isolated sections powered by separate Power Stations.
• Memory Leaks: If the game starts stuttering after 4+ hours of play, restart the application. Prison Architect is known to accumulate “garbage” in the RAM during long sessions.

Frequently Asked Questions (FAQ)

Conclusion and Expected Results

By manually adjusting the preferences.txt to remove shadow masks and simplifying the job search logic, you are giving the Ogre engine the “breathing room” it needs to handle thousands of entities. You can expect a significant reduction in “Work-hour” stuttering, faster navigation through the menus, and the stability required to reach 5,000+ inmate counts.