The word Admins love to hate…




A comprehensive guide to minimizing LAG


By Tentacle-HunteR    ©  2004


This guide is intended to:

1)      Help you wade through & understand all the technical Mumbo-Jumbo.

2)     Give you enough info so you can understand what’s happening without getting too detailed.



Special thanks goes to ReDe@d, & Flawless who helped me test & confirm much of this info.





Section 1 –  Understanding Networks & Unreal.


Fact:  Unreal uses a Client/Server  UDP Connection over the Internet.


To understand why lag happens you need to understand a little bit about computer networks.


Client / Server

·         The Server is the computer that’s hosting the game.

·        The Clients are the players who connect to the server in order to join the game.



·         Stands for:  User Datagram Protocol  (but who really cares?)

·         UDP is a fast way to communicate, because it does NOT establish a dedicated connection between the server and client.   Huh?   How can this be?


This may seem strange so let me explain it this way… 


Imagine someone talking to you while you are busy doing something else.  Because your busy, you may not catch everything they say.  But, of course that person doesn’t realize it and just keeps talking.    You miss out on  information because they don’t have your dedicated attention.


UDP is like that; the connection is NOT forced.  Clients & Servers don’t wait to make sure the other received all the data. They just keep sending it, and sometimes the network is simply too busy & packets of data get dropped.  But,  because it doesn’t have to wait for confirmation, it is a faster way to communicate.



Ping: refers to how long it takes the signal to travel from your PC to the server and back.


·         The Internet is a WAN (Wide Area Network);  the computers are far apart.

·         Clients who are farther away will have a higher ping.



·         Refers to your Internet connection speed:  NarrowBand (Dial-up) or  BroadBand (Cable, DSL, T1)

·         Its like a two lane highway vs. an eight lane super-highway.  The eight lane super-highway can handle more traffic at one time.

·         For a server, it’s the UPLOAD speed that’s important (not your download speed).

·         A slower connection will have a higher ping.






Section 2 –  What IS Lag and What causes it?



So what is Lag?   Lag is when too much data is being sent by the game and the network and/or server can’t handle it all, so game starts skipping or getting slow.   The Network gets Congested & lags (or  slows down) very much like a rush hour traffic jam.



·         What causes LAG?  There are several factors and they include: 

o        Low  bandwidth  (slow network connection)

o        The type of sever your running can affect lag.

o        Too many players for your connection or CPU

o        Downloaders  (downloading uses a lot of bandwidth)

o        Improper network settings (MaxTicksPerSecond & MaxClientRate)



And here’s one that many Admins ignore …


o        Bogging down your CPU resources by  Summoning too much stuff  & Using Weapons that are bandwidth hogs (like some of the Aura weapons)





Section 3  -  How can I reduce Lag?



·         DON’T Go Summon Crazy   & avoid using weapons that spawn a lot of projectiles or effects!


But,  Don’t take my word for it… read these Excerpts directly from  Tim Sweeney (the guy who created Unreal).



Reprinted from: Unreal Networking Architecture by Tim Sweeney

While a tick operation is in progress, the game state is being continually modified by the code which executes.  The game state can change in exactly three ways:

·         A variable in an actor can be modified.

·         An actor can be created.

·         An actor can be destroyed.


Reprinted from: UnrealScript Language Reference  by Tim Sweeney


“Spawning and destroying actors are fairly expensive operations on the server side, and are even more expensive in network games, because spawns and destroys take up network bandwidth. Use them reasonably, and regard actors as "heavy weight" objects.”




·         Type of server:


o        A Listen server – This is the best option for a Dial-Up server.  OK for Broadband servers too.


It will use less Bandwidth, CPU  & Memory resources,  thereby reducing lag.  However,  it’s less stable than a dedicated server  (if your game crashes then everyone gets disconnected).


o        Dedicated Server – for Faster PC’s with more Memory  AND a Broadband connection (DSL, Cable)



o        A Stand-Alone Dedicated Server -  Best and fastest kind of server! 

Yes, I know not everyone can afford a second PC and a network Router.  I’m just saying this is the best way to go.



·         Number of players  (MaxPlayers):    (Note: this is my opinion based on how I have seen various servers run)


o        Dial-up                   -  No more than 3 players.

o        Standard DSL        -  4 – 6 players.

o        Standard Cable     -  6 – 8 players  (I prefer 6 happy players.  Again, my opinion).

o        Business class

Cable or DSL         - Depending on Upload speed 10 – 12 players.

o        T1                          -  If you can afford a dedicated T1 line, then go Hog wild with 20 + players!




·         CacheSizeMegs

This setting tells the Unreal Engine how much RAM to use before spilling over to disk Cache. 




If your running a Stand-Alone Dedicated Server  or a Listen Server then set this to about 2/3 of your Total system RAM.




If you’re running both, a Dedicated Server AND a player game on the same PC then you have two copies of Unreal running and they have to share the memory! …   so, set to NO higher than about 1/3  of your Total System RAM.








MaxTicksPerSecond & MaxClientRate:


What exactly are they?  How do I set them Correctly?



When you install Unreal, it sets MaxTicksPerSecond to 20  & MaxClientRate to 20000.  These settings were intended for a LAN game NOT Internet games!  Lowering these settings  drastically reduces the amount of network traffic flowing across your Internet server network.





MaxTicksPerSecond: (also called TickRate) This is how many times each second the server updates info.


A common misconception is that a higher TickRate improves your ping.   IT DOES NOT!!!!     It only appears to do so!


Lets talk about ping for a second…  Remember, ping is how long it takes the signal to travel from your PC to the server and back.  When your PC sends a signal to the server, it has to wait its turn in line to be processed on the next available “Tick”.  This wait time is added to your ping. 


When there’s too much traffic going in or out of the server then the signals get jammed up and have to wait longer. Again this extra wait time is added to your ping.




So how does a lower MaxTicksPerSecond  help?    Lowering this setting lets the server process data in bigger chunks  thereby reducing the number of requests & updates  between the clients and server.  So, even though your ping might seem slightly higher,   it is more steady because there is now less network traffic.


Lowering the TickRate means fewer updates per second, so initially the ping will appear to be slightly higher.  THIS IS NOT A BAD THING!!!


Think of it like this:  It’s like a 100 people driving their own cars  versus  100 people getting on a couple of busses.     It might take a little longer to load up the busses, but once everyone is aboard, there’s a lot less traffic to cause traffic jams.  This keeps the traffic flowing smoother.




So what should this setting be?   Usually a setting of around 12 to 15  works well  for internet servers.






MaxClientRate:  The rate at which clients are allowed to communicate to the server (based on bandwidth).


First of all, be aware that there seems to be some debated over whether or not this setting actually does anything.  I can tell you this:  Debate all you want, but It DID make a difference for my server!


Ok, so we’ve slowed down the number of times the server is sending updates.  Now  we need to tell the clients to do the same sort of thing.  This is important because if you don’t limit  this,  then clients with a faster connection, or lower ping,  will actually steal bandwidth from others.  Lowering this setting forces all the clients to share the bandwidth equally, and ensures that it matches your connection’s bandwidth.



Think of it like this:


Imagine four people sharing a milkshake.   Two of the people have big fat straws and the other two have skinny straws.  if they are all drinking at the same time, then the two with the fat straws will get more of the milkshake.


Now,  imagine putting caps on the bottom of the two fat straws so the all the openings are relatively the same size.   They will now all  get their fair share of the milkshake.


This will also help ensure that they can’t drink the milkshake faster than you can refill it.




So, What should this setting be?


Epic’s web site says,   Make sure that the MaxPlayers x MaxClientRate is less than your available bandwidth (in the case of cable modems or xDSL, your upstream bandwidth).”



Here’s a good way to test this  for yourself  to see what setting works best for you:



1)  While you have players in you server, simply try a setting of  7,500  and play the game.   Summon some monsters & let the players  fight them.  See how this setting works.


2)  Then increase it to 10,000    or so and test it again.  Repeat this step until players agree that it is getting laggy.



3)  Now simply back this setting off until you consistently get good smooth game-play.


4)  DON’T rush this test!     Be absolutely sure to take a few days to test this fully. 





I have found for my server a setting of about 7500 seems to work very well.  The only time anyone really complains about lags  is when there is a downloader.




Again,  I cannot stress enough, that you need to test these settings out for yourself!