lag hoodoo

This is the first of a series of articles I wrote for the 3rd Rock Grid community newsletter. I'm reproducing it here in hopes that it may benefit a wider audience of virtual world citizens. There is no shortage of articles on lag available through an internet search, but perhaps I will provide a collection of useful information in one place.

While this was written for 3rd Rock Grid, and is thus specific to OpenSim based grids, it will also most certainly be applicable to Second Life as well. At a more general level, much of what will be discussed may also apply to other VWs, such as Blue Mars, or There.com.

Introduction

Lag is a word that is tossed around in virtual worlds as sort of a catch all word for anything that makes the user's experience feel less than immediate. As lag gets worse, the experience of immersion begins to degrade, going from mildly annoying to exasperating to completely unusable.

I hope over the next few weeks to share some of what I've learned in nearly three years of virtual world experience and nearly 25 years of computer experience. I plan to look at what are the sources of lag, and what we as users can do to reduce its effects. While I have learned a lot working for a major computing hardware vendor, and from personal experience in virtual worlds, I certainly don't know it all, and welcome comments, constructive criticism, or additional helpful information. This is especially true for Macintosh systems, as I do not have one. Most of what I say will be applicable, but there may be some details that vary.

Performance degradation is caused by a limitation of computer resources, when a resource is trying to satisfy too heavy a demand. I started to write a lot more detail on this, but we'll save that for later. For now, we'll take a look at a couple of tools that let us see where lag is occuring.

First, there is the Lag Meter. This is sort of like the "idiot lights" on an automobile instrument panel, and is launched from the Help menu of your viewer. The Lag Meter has three indicators, for "Client" (the user's computer), "Network", and "Server" (the computer or collection of computers that run the virtual world). Each of these may be green, yellow, or red, to indicate whether there is a performance problem, and to what degree. Additionally, there is a line of commentary that provides a bit of (sometimes questionable) insight into any problems. Generally, if all three indicators are green, your experience should be acceptable. if one or more are yellow, you may notice some degree of lag, and if one or more are red, you are almost certainly noticing lag.

Second, there is the Statistics Bar. This may be reached with Control-Shift-1 (or Command-Shift-1), or from the View menu as "Statistics Bar". This provides much more detail than the Lag Meter, but parallels its information. FPS (frames per second) is an indicator of client performance, with a rate above 15 corresponding to green, between 10 and 15 to yellow, and below 10 to red.

Likewise, Bandwidth, Packet Loss, and Ping Sim are indicators of network performance, and the various items under Simulator give information about server performance. We'll look at these, plus some others that are normally hidden, in later installments.

I plan to first look at some easy adjustments that can be made, sometimes for a large improvement in performance, and then move on in later installments to some of the trickier adjustments. It is always important to keep in mind that all systems have some maximum level of performance, beyond which no amount of tweaking will improve things, but with careful observation and tuning, we may at least be able to approach that maximum level.

Finally, so that you may have some place to begin this week in improving your virtual world experience, may I suggest that you do some basic system clean up. On a Windows system, run spyware and virus scans, and defragment your hard drives. On all systems, ensure that you are not running large programs or lots of little utilities that, in aggregate, are stealing system resources from your viewer.

Until next time, happy immersion!

~*~

Thoria Millgrove