How to Improve Prison Architect Performance / Lag

This guide is for people who want to maximise performance in Prison Architect.

Whenever this guide says "do X" or "don't do X", I am ONLY considering performance and the ways you can control it. I am NOT saying that doing these things will improve your prison or your game experience. There are other guides and wikis for that.

Following this guide exactly may in fact hurt your experience, so when reading this guide, you have to decide on your own what you're willing to sacrifice for performance. If you're not running a mega prison and not running on a potato, you may prefer to play with settings, mods, and designs that use more CPU but enhance your experience.

No.

Modders do not have the same level of access to the game's code that they might have for other games like Minecraft. Because of this, I do not know of any mod that is intended to improve performance that doesn't sacrifice vanilla functions*. Most mods will in fact hurt performance due to the scripts they need to run, so if you want to maximise performance, you should disable mods which you can live without.

However, there are mods which are worth the potential performance impact, and mods which sacrifice certain vanilla functions for very specific potential improvements.

*2025-09-19: I've since learnt of one such mod, but it deserves its own section. See the Shader Mod section below this section for more info.

Ozone's Fixes and QoL All-In-One is an excellent, high-effort mod which strives to smooth out bugs and annoyances and make the player experience more intuitive, while preserving the vanilla experience and being comparatively light on performance. However, this mod is not intended to improve performance. This mod needs the game to run scripts to fix certain bugs, and running scripts will impact performance, no matter how small the individual impact of one script instance. Players generally report improvements in performance with this mod, but it is still possible for this mod to hurt performance on potato PCs.

Murgh Devtools or Murgh Devtools (Continued) gives options for spawning or deleting many different kinds of objects and entities. You can use it to mass-delete unwanted objects or entities like dead bodies. If you need to edit your save file, you will also need this mod to delete some things to prepare your save file. If you're not deleting things, this mod does not do anything for performance.

There are a number of these on Steam Workshop. The idea is to increase the maximum stack size of e.g. Ingredients, so that there are fewer individual stacks arriving in Deliveries. This also means fewer individual stacks for the game to keep track of, which should improve performance. However, all stack size mods have a tradeoff that the large stacks can't be split: one Kitchen might get 1 stack x 100 ingredients while another Kitchen gets nothing.

That's up to you. See the READ FIRST section of this guide. This applies to anything you might want to do that goes "against" this guide, since there are often good gameplay reasons to do so. Just don't then turn around and complain about lag.

Lenticular Float32 1.2b BETA is a shader mod by jjwalker that brings dynamic lighting to Prison Architect. The description promises large performance increases from updating the base game's use of OpenGL 2.0 compatibility mode to OpenGL 3.0 Core. jjwalker has also mentioned that the mod fixes "the huge slowdown when weather is active and it snows".[forum.paradoxplaza.com]

So why is this mod not in the "Mods For Improving Performance" section? Because I don't experience a drastic slowdown in snowy weather, and I personally noticed no increase or only slight FPS increase with this mod installed. At one point my graphics drivers crashed.

However, I probably made user errors, my hardware is not your hardware (jjwalker also says this in their mod description), and I've seen a few people independently mention large FPS drops in snowy weather. If you have the target graphics setup for this mod, this mod could greatly improve performance.

It also looks pretty.

If you have the snowy weather slowdown, definitely try it. If you don't, you can try it anyway as long as you know the risks. I don't know anything more technical than that.

You will need to do this for many of the tips in this guide. I will mention specific parameters to change in later sections.

1. If cloud save is checked in the Save Menu, temporarily uncheck it
   
2. Save a copy of your prison
   
3. Open the Save Game menu again and click on the file path at the bottom of the list of saved games
   
4. Find your save file and drag it into Notepad++ or similar text editor
   
5. Find the parameter to change, make changes, and save
   
6. Load prison in-game and check if everything works
   
7. Save a copy to cloud if you want

Windows warns you that this may cause system instability.
1. Start Prison Architect
2. Open Task Manager (Ctrl-Alt-Del > Task Manager or Ctrl-Shift-Esc)
3. Right click Prison Architect > Go to details
4. Right click PrisonArchitect64.exe > Set priority > High

You will have to do this each time you start Prison Architect. Making Prison Architect start in High priority every time requires starting it with cmd.exe, registry editing, or a third-party program. I can't recommend any of those options unless you know what you're doing.

I am not familiar with other operating systems.

Graphics:

• Turn off filtering

Game:

• Change autosave frequency to whatever you can tolerate
  
• Turn off Toggle Shadows

Extras:

• Go over your mod list and turn off mods you can live without
  
• Make sure you're not recording a time lapse
  
• Mutators will be covered later

Experimental (credit to @TheIndian_07):

• Turn on Vertex Buffer Objects, save, exit and reload

All objects and entities take up CPU.

Sell or dump boxes and materials which you are not using, or at least make sure your Storage zone is compact. Having boxes and materials scattered over a wide space can cause lag.

If you have large numbers of unwanted entities like dead bodies or unwanted objects like dirty laundry, you can use the Murgh Devtools mod to delete them.

Loops are often used because they look neater, and they prevent single points of failure if you have Events enabled, or if you are hardening your prison against Escape Mode players. However, water pipes have a direction to their water flow. Loops can cause the direction of flow at each point on the pipe to change, which can cause water objects to flicker between connected and not connected. On a large scale or with many loops, it's plausible that the direction changes and object updates would affect performance.

While you may already have a large prison that you want to improve performance for, there are a few things you can consider if you are planning a new large prison:

This helps if you plan to use a stack size mod, as there is less risk of one kitchen hogging all the ingredients or one laundry hogging all the uniforms.

In Deployment view, you want your cells to look like the north cells in this picture (smooth, single cell block), not like the south cells (black lines across the doors, game sees them as individual cells instead of a block):
(In this example, I've used the Empty Room to artificially force the south cells to be individual cells.)

Why? Switch over to Logistics > Food Distribution to see (the example cell block is in centre-left):

Or see Logistics > Laundry Distribution:
The north cells are a single block and can connect to a canteen and a laundry with one connection. The south cells are connected individually to the canteen and laundry, making calculations more complicated.

Some common reasons cells might be forced to be individual cells:

• The cell door opens directly into an outdoors corridor
  
• A room type that doesn't allow grouping has been zoned right up to the cell door

To maximise performance, don't design your cell blocks in these ways.

Unlike cells, dormitories do not group into cell blocks in vanilla. The Ozone's Fixes mod allows dormitories to group.

For best performance, don't buy land expansions.

This obviously might not be the experience you want, so as mentioned at the top, you can decide which parts of this guide you're willing to do.

Note there appears to be an issue where buying too many land expansions will cause job assignments to break, independent of performance as measured by FPS. I have not systematically tested how many is too many or whether "too many" varies with the system.

I have not tested if an unexpanded Large map has better performance than a Small map expanded to the same size. The unexpanded Large map will have a time warp factor applied to make the game time pass slower relative to real time, while the Small map will not, so game time to real time ratio should never be used as a measure of lag.

When starting a new prison, you have the option to enable or disable Staff Needs and Gangs.

These options add more behaviours to your staff and your prisoners respectively, adding more elements to gameplay. But more behaviours means more work for the game. Staff pathfinding for needs especially is very inefficient in large prisons, with staff crossing the prison multiple times to fulfill needs when they already have everything they need in the room they're in.

DLC settings which create new entity and object states and new entities, like Dynamic Reputations (Island Bound), Tropical Fever (Jungle Pack), and Rats (Perfect Storm), while not as intensive as Staff Needs and Gangs, should also be re-considered.

The performance impact of the free DLCs (Free for Life and Cleared for Transfer) is probably not as severe since they don't create new entities or pathfinding, but be aware that they might still have a performance impact.

Read the Save Editing section if you're not sure how to save edit.

Staff Needs: Look for at the top of your save file and set it to or delete it.

Gangs: Use the Murgh Devtools mod to delete all existing gang members, then save. Then look for at the top of the save file and delete it.

Dynamic Reputations: Can be disabled mid-game, though prisoners will keep the reputations they've gained

Tropical Fever and Rats: I have not tested whether existing sick prisoners or existing rats need to be deleted. Look for
(sic)

Prisoner Aging (Free for Life):

Prisoner Transfers (Cleared for Transfer):

Disable all three.

Weather can only be changed mid-game if you have Perfect Storm DLC (it seems the game didn't have code for refreshing the weather table mid-game until Perfect Storm). If you don't have Perfect Storm, you can edit the save file to delete
Temperature and Fog of War can be changed mid-game. You will lose the ability to use hot water for sinks and showers (which affects tray washing speed and sector grading respectively), and you will lose the ability to estimate your guard coverage, as well as the realism. But you spare the game from setting these statuses for every tile.

These are the objects in the Utilities > Wiring tab. I call their wires logical wiring to distinguish them from electrical wires.

Door Control Systems and Door Timers have no hard limit on the number of connections they can have. However, the more connections, the more lag. You will get more performance with more Door Control System objects with fewer connections each, compared to a few Door Control System objects with more connections each. The same applies to Door Timers.

Door Control Systems can only be connected to servos, while Door Timers can be connected to any other logical wiring object.

Think about whether you need to connect a Door Timer to all of your cell doors. Jail doors open automatically when not in Lockup and Sleep when used as cell doors. However, I do use mass Door Timer connections, because I sometimes want cell doors to open during Work-Lockup regime.

You could reduce the number of connections per object by connecting a Door Timer to a few Logic Circuits set to = , and then connecting the Logic Circuits to a few servos each. I haven't tested the performance impact of this compared to using multiple Door Timers.

Floors get dirty over time and are cleaned by janitors and gardeners, for realism and to affect the Environment need of prisoners (and staff, if you have Staff Needs enabled). To turn off decay/floor dirt and spare the game from these calculations, edit the save file to set
DO NOT use the Reduce Dirt Build Up mutator to resolve decay/floor dirt. The mutator runs buggy calculations on tiles and actually decreases performance by 10-15%. ONLY the setting above resolves decay/floor dirt.

Existing dirt will still need to be cleaned. You can wait for janitors and gardeners to clean it or follow Step 4 of @🐶Big-Z🧟's guide to instantly clean it.

You will need a texteditor which supports searching for regular expressions. For example notepad++ would suffice.
Open the 'Find and replace...' dialogue. Ensure it is set to search with regular expressions. Search for 'Con \d+\.\d+' and replace all occurrences with a space. This will clean up your prison.

You will still need janitors and gardeners to handle laundry and forestries respectively, but you might not need to hire as many.

You can edit the save file to place in the list of parameters at the top, so that materials teleport into Deliveries and teleport to building workmen, making construction faster. This was default behaviour prior to Island Bound's release. The Ozone's Fixes mod adds a staff member, the Construction Specialist, which allows you to toggle this flag without opening the save file yourself.

Alternatively, you can use the Fast Deliveries mutator, which causes all objects (ingredients, workshop metal plates, etc.) to spawn in Deliveries, eliminating transport jams and unloading jobs. This mutator may not cause building materials to teleport to workmen.

This mutator makes all entities (prisoners, staff, visitors) walk faster relative to game time. It might help them to clear jobs faster, but it might not noticeably improve performance either.

This mutator allows staff to walk through walls, which greatly simplifies their pathing, but is not realistic at all.

Enabling cheats to make all construction instant may be, well, cheating, but it will greatly cut down the number of jobs that the game has to handle.

Edit the save file to add the following in the section at the top:

If I knew, I would have included it in the guide.

Feel free to comment if you've tested something that I haven't.