SecondLife's list of DOs & DON'Ts reguarding 'lag'

Author's Note: I inserted this here because everyone comes to the general forum when they are new. Everyone always takes a peek. I wish to make this more of a common knowledge thing instead of a support thread. Heck... maybe we can get this 'stickied' one day.

Thread written by Nexus Nash & Llauren Mandelbrot. If you ahve anything to add or if you have found a good reference please PM Nexus Nash

PURPOSE
The purpose fo this thread is to compile a lists of DOs & DON'Ts reguarding 'lag' prevention when playing SL.

'LAG' DEFINED
'Lag' defined: Wikipedia - Lag
'Lag' defined: BadGeo - Lag This is a MUST read for anyone creating anything in SL.

INSTRUCTIONS
Please refrain from posting more then once; instead EDIT your post to add stuff. Trying to build a nice clean list. (I know it's a universal impossibility on a forum, but hey, I can try! ) Also, make a colum for serverside and clientside.

Please try to stay in the scope of improving preformance.
Please avoid writing giant paragraphs or tutorials. Instead link them as a reference. Trying to keep this short and sweet, if someone wants more info, they will click on the link.

COLLECTED WISDOM

Determine the type of lag
The first thing to do when encountering lag is to pin down whether the 'lag' you are experiencing is client or server side. A good place to start is checking the statistics bar. [link contributed by Isablan Neva] In SL we have two types of 'lag' or slowdowns: serverside and clientside.

1. ServerSide: This is caused by the server or sim/simulator/island you are currently on. In short, the server gets overwhelmed by request/instructions and is unable to process them fast enough. This is when the client waits for the server, thus causing the delay and slowdown.
   
   
2. ClientSide: This is when your computer (yes yours, this is totally your fault! ) is unable to process and render the information provided by the server faster then 25FPS, (your eyes have a refresh rate of 25FPS, I think) so you see visible slowdown and choppyness on your screen. What causes your computer to 'lag': too many textures to render at once and too many polygones to render at once (ground, avatars, objects).
   

Telling the Difference [contributed by Hiro Queso]
More often than not, in my experience, performance problems are clientside. The answer to this question also answers the question as to whether the individual has to fix problems, or the land/objects owner. They're not always one and the same. Unfortunately, some serverside problems are not always in the hands of either, but in those of neighbours. The problem, though, is most assume the later first off.

SERVER SIDE ISSUES

1. Learn to read the statistics bar. [link contributed by Isablan Neva]
   
2. Don't use llListen in the main chat unless it has a 'passive' mode. If the listen is always active it will process everything if it's not filtered!
   
3. Use pre-exiting LSL functions instead of creating your own. IE: use llListFindList instead of a for loop. If a built-in function can do it at all, it can do it much faster than anything you can write.
   
4. Keep your simulator to a 30 to 40 user maximum
   
5. Keep physical objects in check or try to avoid using them.
   
6. Keep scripts to a minimun when possible: Scripts simply existing in-world in any kind of "running" state contributes to script-lag. At least script-lag doesn`t [usually] have any affect on world-lag these days. See "dormant" scripts aren't as dormant as you think for details.
   

CLIENT SIDE ISSUES

1. Don't use 1024x1024 textures when 64x64 texture would be sufficient.*
   
2. Don't use 32bit textures when 24bit will do.*
   
3. Avoid using prim hair. (i'm talking like 256 twisted hollowed tori("toruses") more...
   
4. Avoid using excessive particles (reference to 'Bling') anyone with a bling link?
   

SIDE NOTES

Texture Issues [contributed by Caliandris Pendragon]
Restricting the size of textures (never using a texture bigger than 512x512, trying to use smaller) and restricting the number of textures used, will both have an effect. Choosing a standard set of textures for use in a sim will help. If you have lots of ever-changing vendor boxes, I'd see that as a two-fold problem, for the scripts, and for the textures.

The Primitive Type
Primitives are composed of triangles. Complex prims such as tori (toruses) render with many more triangles than do simple prims like cubes. More complex primitives take more rendering time from your GPU (graphics card).

Space for future stuff.

I think a good start would be if someone could write a few words on how to pin down whether the 'lag' you are experiencing is client or server side, though that ties in with reading the sim stats of course. I would write something, but am sure there are some who are better 'qualified' to write a concise version.

I am ready to be beaten around the head with a Lag for Dummies book...but I really don't understand why the distinction between server and client side lag. If the fact that you have used hundreds of large textures causes a problem to visitors to your sim, shouldn't you do something about that? Even though the lag is client side?

Restricting the size of textures (never using a texture bigger than 512x512, trying to use smaller) and restricting the number of textures used, will both have an effect. Choosing a standard set of textures for use in a sim, will help. If you have lots of ever-changing vendor boxes, I'd see that as a two-fold problem, for the scripts, and for the textures.

Restricting the number of alpha textures, also has an effect on the performance for the visitor. Some are worse than others...only experimenting with adding and removing will show if the ones you are using are a problem. We had one texture that caused immense problems in Numbakulla, for no logical reason we could see.

One of the things that I was told that surprised me was that the number of prims has a big effect on lag. If you use all 15,000 prims in a standard private island sim, then that may be a problem. I rebelled against this idea, but it is true: for best performance you need to leave 2-3K prims unused in a standard-size sim.
Cali

Because that *has* to be the first question to ask in determining where an individual's problem lies. I suppose it depends if you are writing a 'hints and tips' for 'lag' in general, or trying to solve a persons performance problems. More often than not, in my experience, performance problems are clientside. The answer to this question also answers the question as to whether the individual has to fix problems, or the land/objects owner. They're not always one and the same. Unfortunately, some serverside problems are not always in the hands of either, but in those of neighbours. The problem, though, is most assume the later first off.



On the scripts part: Yes, that certainly adds to performance problems, but I have often found the worst scripts are those you would not expect to be, simply because they're poorly written. I am far from an expert on the impact on performance by scripts, but I do know that you often have to treat each instance on a case by case basis. Performance problems due to scripts is an area you could get into some serious depth over.




I remember you bringing this up before, have you ever had an explanation as to probable cause?



This is another black and white area. The prim shape will be all-important in determining the extent of a performance hit clientside. I bet it wouldn't take many tortured tori to equal the amount of 'lag' 15k cubes presents.

Just a note on prim/texture/particle issues: Bling is only a drop in the bucket in general compared to some of the horribly overdone clubs I've seen. Spotlights look great when you're the only one in the club, but if they're not built right they actually hamper camera manipulation. And dance floors with texture motion effects are a load on the eyeballs as well as graphics card.

The best clubs I've seen don't rely on the eye candy. Good people, good music, and reliable hours will draw fans far more than a psychedelic dance floor.

Second note on prim hair: The better hair builders know this already, but every time you twist a torus you're twisting my graphics card too. A reasonable limit would be around 20-30 prims per hair, maximum. Anything over 100 prims threatens to crash people around you. If you think this is an exaggeration, you should have been with me in ETD's last week when I was shopping for more hair (sigh), and a girl walked past me with the longest, curliest (and cute) hairstyle I've ever seen. For a solid 10 seconds I couldn't move. I wanted to offer to buy her a new hairdo with fewer prims just to save SL.

Last word for landowners: Want to know what's taking up the cycles on your land? Scan-foo!

*applauds your use of the word "tori"*

excellent read!

http://www.kuffner.org/james/gallery/raytracing/torii/torigate9.jpg

Step 1. get lag

step 2. ask the person beside you "are you lagged?"

step 3. if they say no.. then its you.. if yes.. then the sim O.O;;

or am I missing something

**edit**
I guess since Im bored I'll add my own Do's and dont's

DO not ever put your draw distance past 64 unless on an empty virgin sim (and if you do this be sure to drop it back before Tping into the welcome area)

DO not ever.. no matter how curios you are.. try creat a high rez snapshot.. Images from SL do NOT need to be 200mb

DONT EVER go near the Edge/bad girls or anywhere with the words bling, hiphop(these being preference and nothing to do with lag), or camping chiars in the description

Here would be that statitics bar link:

http://secondlife.com/tiki/tiki-index.php?page=GuideDebugStats


Edited to add Preferences Guide:

http://secondlife.com/tiki/tiki-index.php?page=Preferences+Guide

Uh.. how many people actually know how to use ctrl-alt-1?

....

I was under the impression that vendors with X number of products and very low lag scripts were better than X number of boxes on the wall. With fifteen product boxes, for instance, fifteen textures get loaded whether you like it or not. With fifteen products in a vendor, only one of those textures has to be loaded unless you or someone else clicks on the vendor.

Have I been mistaken in this? Or were you only referring to the kind of vendor that cycles through textures on its own?

Yes, with a well built script, vendors are better. Reason: less textures to stream (server and client (to render)) less prims to render for the client. As for the script, if it's well built, it's worth the 'image time' it saves the server.

Not sure this fits but I was having problems with crashes after I had been log in to SL for awhile. I checked the webpage of the pc vendor and he had a FAQ for crashes while running software.

I was amazed to learn that my problem was that dust had collected inside the pc. I had to remove the cover and use canned air to blow the dust out.

The improvement in the performance in SL was amazing.

I thought I would add the info just in case I was not the only one who did not know this.

For an extra Boost, use CTRL+SHIFT+ALT+D to bring up the Debug menu, and use that to turn off certain renderable objects like clouds, grass, trees, etc.

Client lag, server lag... and no mention of network lag? If the plan is to make a useful resource on lag then you'll need to explain teh basic of netwrok lag and dropped packets. As someone who hits 30% packet loss occasionly, it has a massive impact on performance.

What about use of the "Full Bright" option? I've heard this causes MASSIVE lag.

Fact or Fiction?

Christ I hope not!

Using the debug menu and turning off alpha rendering will give you a decent performance boost, at the cost of transparent objects and some other things. Prim hair, crap like that. This could just mean the difference between fun at a club, and lagging the night away.

Apologies if this has already been mentioned:

1: turn off any shields and interceptors that you don't happen to be using.
2: if at all possible, remove shields and interceptors you don't happen to be using, along with animation overriders, hug scripts, weapons, etc, that you do not require for your appearance or will not need to use at quick notice in the forseeable future.
3: Leave listens out of poseballs. You can perfectly easily hide pose scripts within the furniture itself, or have the poseballs remain invisible at all times (you'd rightclick-sit the seat, not the ball). Less lag AND prettier (poseball flocks...ugh).
4: Tell Musuko Massiel how wonderful he is. It'll give you an instant 2fps boost.

Musuko.

Fiction. Full bright is the solution to the so called 'massive' lag caused by lights.

This is wonderful! Thanx to those who contributed, credited duly above.

Since this pertains to the more complex underpinnings of SL, I'm moving it to Technical Issues.

These things have come up many, many times and it'd be fantastic to have a focused thread...

and in saying this, it's been made a STICKY!

i would like to insist again on the prim hair problem because to me it seems to agrivate with heavier and heavier hairs, peoples need to understand SL's engine CANNOT render every strand of hair in real time and keep the framerate acceptable, and the automatic prim degradation make big hicups on prim hairs.

(If only there was something like torus prims costed 5 prims instead of 1, it might dissuade to use them in too large quantity...)

Too bad you have to do that EVERY login..
Would it be possible to maintain those settings ?