New example script to show this effect - watch how the clouds increase over time:
//--------------------------------------------------------------------------

startParticles()
{
llParticleSystem([
PSYS_PART_FLAGS, 0 |
PSYS_PART_INTERP_COLOR_MASK |
PSYS_PART_INTERP_SCALE_MASK |
PSYS_PART_WIND_MASK |
PSYS_PART_FOLLOW_VELOCITY_MASK,
PSYS_SRC_PATTERN,PSYS_SRC_PATTERN_EXPLODE,
PSYS_PART_MAX_AGE,15.0,
PSYS_PART_START_COLOR, <0.05,0.05,0.05>,
PSYS_PART_END_COLOR, <1.0,1.0,1.0>,
PSYS_PART_START_SCALE,<4.0,4.0,4.0>,
PSYS_PART_END_SCALE,<15.0,15.0,15.0>,
PSYS_SRC_BURST_RATE,1.5000,
PSYS_SRC_ACCEL, <0,0,0.175>,
PSYS_SRC_BURST_PART_COUNT,100,
PSYS_SRC_BURST_RADIUS,2.0,
PSYS_SRC_BURST_SPEED_MIN,0.5,
PSYS_SRC_BURST_SPEED_MAX,1.5,
PSYS_SRC_TARGET_KEY,(key)"",
PSYS_SRC_INNERANGLE,0.0,
PSYS_SRC_OUTERANGLE,0.0,
PSYS_SRC_OMEGA, <0,0,0>,
PSYS_SRC_MAX_AGE, 0.0,
PSYS_SRC_TEXTURE,"",
PSYS_PART_START_ALPHA, 0.6,
PSYS_PART_END_ALPHA, 0.0
]);
}

default
{
touch_start(integer total_number)

}
//---------------------------------------------------------------------

It almost looks like the particles are delayed in starting. In another test I have a popgun that shoots a ball which has a "plasma" type particle script. In 1.19.0 (79674) the ball shoots out and a little later the particles appear, whereas in the previous Windlight and in the current RC the particles appear as soon as the ball is shot.

particles(key lightningTarget) // particles for the chain effect. the target is sent by mainObj
{
playSound();
integer bounce = 0; // Make particles bounce on Z plane of object
integer glow = 1; // Make the particles glow
integer interpColor = 1; // Go from start to end color
integer interpSize = 1; // Go from start to end size
integer followSource = 0; // Particles follow the source
integer followVel = 1; // Particles turn to velocity direction
integer wind = 0; // Particles affected by wind
integer pattern = PSYS_SRC_PATTERN_ANGLE;
key target = lightningTarget;
float age = 0.25;
float maxSpeed = 0; // Max speed each particle is spit out at
float minSpeed = 0; // Min speed each particle is spit out at
string texture = ""; // Texture used for particles, default used if blank
float startAlpha = .75; // Start alpha (transparency) value
float endAlpha = .75; // End alpha (transparency) value (if interpColor = TRUE)
vector startColor = <1,1,1>; // Start color of particles <R,G,B>
vector endColor = <1,1,1>; // End color of particles <R,G,B> (if interpColor = TRUE)
vector startSize = <3, 3, 0>; // Start size of particles <x,y>
vector endSize = <3, 3, 0>; // End size of particles (if interpSize == TRUE)
vector push = <0,0,0>; // Force pushed on particles
float life = 0; // Life in seconds for the system to make particles
integer count = 1; // How many particles to emit per BURST
float rate = 0.06; // How fast (rate) to emit particles
float radius = 0.0; // Radius to emit particles for BURST pattern
float outerAngle = 0; // Outer angle for all ANGLE patterns
float innerAngle = 0; // Inner angle for all ANGLE patterns
vector omega = <0,0,0>; // Rotation of ANGLE patterns around the source
integer flags = 0;
if (target == "owner") target = llGetOwner();
if (target == "self") target = llGetKey();
if (glow) flags = flags | PSYS_PART_EMISSIVE_MASK;
if (bounce) flags = flags | PSYS_PART_BOUNCE_MASK;
if (interpColor) flags = flags | PSYS_PART_INTERP_COLOR_MASK;
if (interpSize) flags = flags | PSYS_PART_INTERP_SCALE_MASK;
if (wind) flags = flags | PSYS_PART_WIND_MASK;
if (followSource) flags = flags | PSYS_PART_FOLLOW_SRC_MASK;
if (followVel) flags = flags | PSYS_PART_FOLLOW_VELOCITY_MASK;
if (target != "") flags = flags | PSYS_PART_TARGET_POS_MASK;
llParticleSystem([ PSYS_PART_MAX_AGE,age,
PSYS_PART_FLAGS,flags,
PSYS_PART_START_COLOR, startColor,
PSYS_PART_END_COLOR, endColor,
PSYS_PART_START_SCALE,startSize,
PSYS_PART_END_SCALE,endSize,
PSYS_SRC_PATTERN, pattern,
PSYS_SRC_BURST_RATE,rate,
PSYS_SRC_ACCEL, push,
PSYS_SRC_BURST_PART_COUNT,count,
PSYS_SRC_BURST_RADIUS,radius,
PSYS_SRC_BURST_SPEED_MIN,minSpeed,
PSYS_SRC_BURST_SPEED_MAX,maxSpeed,
PSYS_SRC_TARGET_KEY,target,
PSYS_SRC_INNERANGLE,innerAngle,
PSYS_SRC_OUTERANGLE,outerAngle,
PSYS_SRC_OMEGA, omega,
PSYS_SRC_MAX_AGE, life,
PSYS_SRC_TEXTURE, texture,
PSYS_PART_START_ALPHA, startAlpha,
PSYS_PART_END_ALPHA, endAlpha
]);
}

Sorry mine is a bit messy, but if you look at the beginning of the function you should get a clearer idea of what my settings are. Most notably I am using PSYS_SRC_PATTERN_ANGLE unlike the other posted examples and I am having similar effects of not enough particles being emitted. The rate for the particle burst is at 0.06 and it's very obvious from watching the effect in action that this is not the case whatsoever.

In addition to this, I would add that I have had to tweak DOWN several parameters in my previously scripted particle emitters - bonfire, waterfall, fountain etc. - using a mist/smoke cloud effect. on integer pattern = PSYS_SRC_PATTERN_EXPLODE. Windlight (for the past 3 releases) turned these emitters into huge particle clouds and I had to reduce vector endSize, vector push and integer count to get the emissions to look the way they did in main client.

Of course the corollary to this is that now they barely emit at all in main client, so you get a completely different effect depending which viewer you're using. This does not seem a good thing!

Do stop by my land (Songnisan 135,14,80 "Dragonsong") to compare these results. Note that I haven't rescripted the fountain on sale in my vendor so that's currently steaming like a cauldron in windlight!

The lower image is the previous windlight client. As in, the previous incarnation of this bug.

The upper image is taken today in the new 1.19.1 RC with all the same settings and maxed out particle count.

Notice the horrendous lack of particles on the blue fan shaped part, and the reduced number of the grey needlelike bits.

This effect does not seem to get better with time either.

I discovered today that it had set my max particle count WAAAY too low from autodetecting. And that the degradation in particles I saw was caused by this.

Particles are still not working right, but they have not gotten worse in this version, as I initially expected

WindLight recently "graduated" from a "First Look" technology preview to Release Candidate status – nearing inclusion in the main viewer with your help! So, "First Look: WindLight" does not exist anymore.

More info and how to download the RC viewer: http://blog.secondlife.com/2008/03/06/new-release-candidate-viewer-1191-rc0-available/

If you've verified that this issue is still a problem in the newest Release Candidate, here's what to do next:

(1) Search the Issue Tracker to make sure it isn't a duplicate of an existing issue we know about. If it is, link it as a duplicate using the "Link this issue..." link on the left. You can learn more about searching by watching this video tutorial: http://www.youtube.com/watch?v=SAlXK5hSVMc

(2) Reopen the issue and BE SURE to update the "Affects Version/s" to the correct one, most likely ONLY "1.19.1 Release Candidate". However, if this bug affects the main viewer (1.19.0 as of this writing), then DO NOT set it to an RC version. Only set it to 1.19.0 instead. Be as specific with versions as possible – there's generally no need to set multiple versions, as it tends to dilute and confuse where a bug originated.

(3) Add any other relevant details that would help us fix it. We can't stress the importance of a "solid repro" enough – a reliable series of steps to make a bug happen reliably.

(4) Come and attend our inworld bug triages, where you can meet with Linden Lab employees to look at, verify, and expedite bugs for fixing. More info @ http://wiki.secondlife.com/wiki/Bug_triage

Thank-you for helping us improve Second Life!

fireParticleOn() {
llParticleSystem([ PSYS_SRC_TEXTURE, "168e6813-096e-07ea-97ae-fd416826f627",
PSYS_PART_START_SCALE, <.1,4.0, 0.1>,
PSYS_PART_END_SCALE, <.1,4.0, 0.1>,
PSYS_PART_START_COLOR, <1,0,0>,
PSYS_PART_END_COLOR, <1,0,0>,
PSYS_PART_START_ALPHA, 1.0,
PSYS_PART_END_ALPHA, 1.0,
PSYS_SRC_BURST_PART_COUNT, 20,
PSYS_SRC_BURST_RATE, 1.3,
PSYS_PART_MAX_AGE, 4.3,
PSYS_SRC_MAX_AGE, 0.0,
PSYS_SRC_PATTERN, 4,
PSYS_SRC_ACCEL, <0.0,0.0,0.0>,
PSYS_SRC_BURST_SPEED_MIN, 30.3,
PSYS_SRC_BURST_SPEED_MAX, 30.3,
PSYS_SRC_ANGLE_BEGIN, 0*DEG_TO_RAD,
PSYS_SRC_ANGLE_END, 0*DEG_TO_RAD,
PSYS_SRC_OMEGA, <0,0,0>,
PSYS_PART_FLAGS, ( 0

fireParticleOff() {
llParticleSystem([]);
}

default {
state_entry() { fireParticleOff(); }

touch_start(integer num_detected) { fireParticleOn(); llSleep(0.3); fireParticleOff(); }
}

Touch the script and see the difference between the Standard Viewer and the Release Candidate. Do the same with a bling script and you will notice similar behaivour, even though not as noticeble, since it appears that the problems gets better over time.

There have been so many bugs with particles in Windlight that its hard to say if this issue links to another, but test the script out and see for your self.

My System:
CPU: Intel Core 2 Series Processor (2666 MHz)
Memory: 3071 MB
OS Version: Microsoft Windows XP Service Pack 2 (Build 2600)
Graphics Card Vendor: NVIDIA Corporation
Graphics Card: GeForce 8600 GT/PCI/SSE2
OpenGL Version: 2.1.1
LLMozLib Version: [LLMediaImplLLMozLib] - 2.01.13604 (Mozilla GRE version 1.8.1.11_0000000000)