User:Lou Montana/Sandbox

Introduction

This article will try to be a general guide about improving your mission's code and its performance.
As usual, moderation is the key so do not expect to have thousands of AI magically running 144 FPS. Everything comes at a cost, the tweaks on this page will simply allow you to calibrate your mission properly.

ⓘ

This page is about Mission Optimisation. For scripting optimisation, see Code Optimisation.

ⓘ

See also Multiplayer Scripting.

Before anything

Before optimising anything, make sure you do not have any performance issue running the game itself:

• Open the editor, place a unit in the area you like and test your computer.
  • Arma 3 displays FPS when you go into video options
  • Steam allows you to display FPS in a screen corner, in Settings > In game > FPS Counter
• Use (unofficial) Performance Guides to get better performances:
  • Arma 3 performance guide
  • Arma 2 performance guide
  • Arma performance guide
• Play your mission in singleplayer. If your mission runs fine, its network messages might very well be the issue. See Multiplayer Scripting for good practice tips.
• Usual bottlenecks:
  • Lower your graphical settings (resolution, textures). If you get way better performances, at least your GPU limits you.
  • If the game keeps having low FPS when running @ 1024×768/low textures then your CPU is most likely the issue. Mission scripts may be performance-hogging too.

⚠

Please note that viewDistance (among other settings) impacts both GPU and CPU!

Creating your mission

• Be sure to create your scripts with the latest available commands and functions.
  • In Arma 3 use remoteExec / remoteExecCall and DITCH BIS_fnc_MP FOR GOOD! See Arma 3 Remote Execution for more information.
  • In Arma 2 network communication is done using the Multiplayer framework.
• Use the available frameworks and functions for each topic, unless you replace them by third-party ones:
  • Arma 3 Respawn
  • Arma 3 Revive
  • Arma 3 Task Framework
  • Arma 3 Animated Briefing
  • Arma 3 Animated Opening
  • Arma 3 Dynamic Groups
  • Arma 3 Key Frame Animation
  • and most importantly: Functions

Performance impact table

Topic	CPU	GPU	Net- work	Solution
AI units quantity	Template:colorball	Template:colorball	Template:colorball	Use Agents whenever possible The more units there is, the more network update there will be - hence the impact on both CPU and network. If a client has a low-end machine, they shouldn't lead a group of many AIs as these would then be locally computed. Arma 3 Dynamic Simulation allows you to freeze AI that are distant from players. Many distance settings should be set according to the mission. ⚠ Most if not all of the mission calculation (objectives, completion distance, etc.) must be done server-side. Local effects should be calculated client-side. ⓘ If you own more than one average computers, you could consider Headless client to offload AI from the server.
Objects quantity	Template:colorball	Template:colorball	Template:colorball	The less objects, the more FPS you will have. Lower the mission objects quantity AI units, agents vehicles, simple objects weapon attachments (their proxies are attachedTo) headgear, clothing, vests, backpacks head-mounted devices (NVGs, etc.) Lower viewDistance Lower terrain details Lower the Dynamic Simulation treshold Use Simple Objects Use Garbage Collection in order to automatically delete bodies and wreckages: Arma 3's Eden-integrated Garbage Collection Arma 2's Garbage Collector Take On Helicopters's BIS_fnc_GC ⓘ only the on-screen objects will strongly impact GPU.
High-frequency scripts	Template:colorball	Template:colorball	Template:colorball	A while-loop checking without a minimum loop-sleep time is usually a sign of bad conception. Does your code execution need to be frame-perfect, or can you afford a delay of one second? while { true } // already "bad" if you don't know what you are doing while { alive player } // better while { sleep 1 ; alive player } // perfect Triggers check their set condition every 0.5 second (hardcoded value). If a large area is covered or condition code is too complex, this can be an issue. Convert them to scripts then.
High-frequency network messages	Template:colorball	Template:colorball	Template:colorball	Use publicVariable wisely; for specific cases, consider publicVariableServer / publicVariableClient Creating units/vehicles globally implies a network synchronisation, keep them to a minimum / at one-point in the mission. keep the command with a global effect to a minimum: e.g a setPos will synchronise the unit position to every client, a good practice is to use these commands punctually. If you need a frequent "set position" you may want to look at attachTo depending on your usage. Lower client's view distance in order to lessen its object position update requests

ⓘ

View distance can be separately set for each clients independently from the server's value, through scripting.
This can make or break performance for the client.

What else?

You have applied all these recommendations and yet, your mission still doesn't run well in multiplayer (but does in singleplayer); an answer to that is that you are using mods, of which some are not well optimised, if at all.

If you want to be sure, run the same mission with and without mods. If you have a big difference in performance, look no further.