Render weight basics for Second Life

27 Feb

The opinionated post I made about render weight two weeks ago continues to get a stream of traffic, almost entirely from search engines. It seems that Second Life residents are very curious about this topic and I’ve heard from both newbies and old-timers who don’t understand it at all. If that’s you, you’re in excellent company! Let me see if I can take a step back and help make this easier to understand.

What is render weight?

In basic and practical terms, it’s an indication of how much work your computer does in order to render (display) something. So, the impact of render weight hits you and me and everyone else running a viewer. It can be experienced as slow rezzing and graphic glitches, which we might blame on sim lag when it’s actually the effect of rendering a lot of complex avatars and things. If your video card is using resources trying to render someone’s elaborate shoulder pet, those are resources it can’t yet use to show you the scenery or the person standing behind him. The effect will vary based on your GPU and graphics settings, but people have suggested that lowering render weight can have similar effect to upgrading your video card, without the expense.

Game time!

Can you match the render weight to each of the hairstyles below? These are all from my inventory, from 8 different makers, and are all one-piece mesh with the exception of E, which has a flexi attachment. In ascending order, the render weights are 1156, 1448, 1758, 2207, 15171, 28442, 31545, and 63338. Can you tell which are low and which are high?


A quick note: I’m not going to name any brands. I deeply admire the work of creative people in SL and I don’t think anyone should be considered “bad” because of a high render weight item. There’s a time and place for those. However, I think render weight should be disclosed by makers just like land impact is, so that consumers can include that in their decisions.

How to see render weight

In the official viewer (according to the SL Wiki): To see avatar weights, open Me>Preferences… from the main menu. Under the Advanced tab, enable “Show Advanced Menu”. Back at the main menu, pick Advanced>Performance Tools>Show Draw Weight for Avatars.

In Firestorm: Open Preferences from the Avatar menu. On the Advanced tab, enable “Show Advanced Menu”. Back on the main menu, choose Advanced>Performance Tools>Show Render Weight for Avatars.

With either of these, you should now see render weight and information floating over the head of each avatar (e.g. “textured_and_downloaded 44336”). Color coding from green to red indicates how close the number is to Linden Lab’s optimal range. This will reset whenever you log off or you can go back to the Advanced>Performance Tools menu and uncheck the option to get rid of the numbers.

Where does the weight come from?

A classic SL avatar wearing nothing but system layers and system body parts has a render weight of 1000. The SL mesh avatar “Sara” with her initial mesh outfit has a render weight of 10556. After that, the calculations start to get more complex. The technical explanation is here in the SL Wiki: Mesh/Rendering weight. Essentially, there is a base cost calculated by the density of shapes (triangles) in the item, and then the cost of each prim is multiplied depending on other rendering factors, such as if it is shiny, animated, flexi, etc. Unique textures, particles, and media are counted for each prim, too.

While some people might be able to guess render weight at a glance, I can’t. I have gorgeously detailed dresses with lower render weight than very simple pants. Spheres and curves can be triangle-heavy because it takes a lot of those sharp little buggers to make something look smooth.

Below is my main avatar in an outfit with low render weight, totaling 18358.


The 18358 total is comprised of these elements:

  • 5372: mesh skirt
  • 3710: mesh shoes
  • 2336: mesh hair
  • 2152: attachment eyelashes (upper only, not sure if mesh)
  • 1776: mesh fingernails
  • 1608: mesh feet
  • 404: ankle lock (invisible!)
  • 1000: base avatar plus system top, tattoo layer makeup, eyebrows, and hair base

Let’s go back to the hairstyle question I asked above. Were your answers close?


These styles are all from my “Hair/Long and down” folder and while they aren’t identical, they have a lot of similarities. If I choose one of the 4 lowest weight styles, I’ve got more room to customize my avatar, but I can make E, G, and H work. I’m not always a render-conscious shopper, but with hair, I’ve found that demo versions tend to be close to the render weight of the final product. Try a demo first, check how it changes your render weight, and decide if that number works for you. Personally, I’ll be purging the 63k hair from my collection. It looks nice with tiaras and some hair accessories, but I have enough other options. (Hi, my name is Kay, and I’m a hairstyle addict….)

Why care about render weight?


Two nights ago I saw an avatar with a render weight over 900k (I’m not including a photo of her avatar because I don’t wish to embarrass her, but her displayed render weight is above). She was wearing a system dress that I also have — a store gift — so I know it has a render weight of only 872 for the skirt prim. What caused her incredible total?  I tried not to be overly rude by inspecting her closely. She had mesh breasts, flexi hair, shiny shoes, and blingy jewelry. This wasn’t a new resident; she had been in SL more than six years.

My avatar had a render weight of 44k that night, so in comparative terms, for the same resources it would take to completely render her, my computer could render about 20 versions of me. When I’m in an area with few avatars and simple surroundings, render weight isn’t very important. However, if I go to a busy club or a festival or a popular sales event, where there are thousands of objects and dozens of avatars to render, it matters a lot. (Best outfit for a busy sale or hunt, in my opinion? I take off everything I can and put on a full body alpha layer. The result is a default render weight of 1000 but I’m invisible, hiding my ugly default parts and lack of AO. If you need a full body alpha, send me a note in SL and I’ll give you one.)

If you’ve put time into customizing your look, you probably want people to see it. Keeping your render weight moderate makes it easier for others to view your fantastic self. Also, there is a tool being tested by Linden Lab that automatically downgrades the appearance of other avatars above a certain render weight, determined by the capabilities of your GPU. If that comes out, would you rather appear to most people as the avatar you prefer, or as a “colorful silhouette”? Your avatar would look fine to you, but to others, you might look like Green Man.

What is a good render weight?

My opinion, like I said above, is that it depends on the situation. The render weight colors seem to shift out of the green zone around 15k and turn pure red at 40k. When I’m exploring the grid, I aim for under 25k with my main avatar because I can — she has a simple look. With my alts, I try to stay under 60k. That’s still much lower than most avatars I see. At home, where I’ve got a chunk of a region with just Jakob and me in it, I can pile on jewelry and attachments and multi-tiered flexi skirts if I want to. If you want to read more about basic and advanced techniques to reduce render weight, I’ve got links in my previous post.

Why the hell is Kay writing about this again?

I have no intention of becoming a render weight activist. Wear whatever you want! It’s your Second Life. My partner has worn the same outfit every day for more than 2 years — it has a render weight around 127k and he couldn’t care less about changing it. I’m not the render weight police.

So, I’m writing for one reason: to inform. If you understand the issue, you can make knowledgeable choices for yourself.

Rock on. If you so choose.


Posted by on February 27, 2015 in Side Topics


Tags: , , , ,

5 responses to “Render weight basics for Second Life

  1. girlforgetful

    February 27, 2015 at 11:04 am

    Since your last I’ve discovered the render weight menu item and have been paying close attention to it. I was surprised I came in at over 60k because I equated cheap with low prims (I love a bargain). I often have issues with graphic rendering in busy places and now I have an idea why. I think I will be asking you for that full-body alpha not only to minimize my impact, but also because I like the idea of exploring in stealth mode after a run-in with a nasty little mushroom and an Alien avatar that accosted me earlier this week (I LOL’d but it was kind of annoying and rude). I took a class at Builder’s Brewery last weekend and the instructor asked everyone to remove everything with scripts to reduce lag. I wasn’t sure, though, what that meant for me. Does anything with a menu Hud or animations and/or bling cover that? Do mesh shapes and skins have scripts? Do scripts require additional prims? I’m sure I could find out on my own but since you’ve already done the research … 😉

    • Kay

      February 27, 2015 at 11:29 am

      Scripts are a topic for another epic rant someday. 😉 Briefly, though, one nice thing about scripts is that it’s easy to see exactly what you are running. Click “Land” from the menu, or right-click on the ground and choose “About Land”. At the bottom of the pop-up, click “Script Info”. Then, choose the “Avatar” tab. This will tell you exactly what items you’re wearing that have scripts and how big each script is in kilobytes. Most attachments have scripts, but the scripts in a mesh body are tiny compared to a multi-AO HUD or a default OpenCollar item. When you see the list, you can detach the highest items and feel pretty good about your count. 🙂

      I’m finding that a lot of people think that inexpensive, older, or “simpler” items will have a lower render weight. I did, too!


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