Looks very nice to me. Would be great for a shmup! :D

I was able to get it running on both my 1st gen and 3G S, though the difference in performance between the two was quite obvious. Keep in mind too, that just because you see lots of 'particles' flying around, doesn't mean there are actually particles flying around. You could create a big png file with hundreds of 'particles' in it and simply have it moving about the screen, or have 4-5 for that matter which would be a considerably smaller performance hit than hundreds of particles.

Just for fun I added print(#stars) at the end and it gave me 600 as the number of objects floating around the screen. The sample code for fishies will let you change the number of fish as well and it bogs down pretty good around that number. Generating that many objects on the fly (while nifty) isn't very efficient. This really isn't a corona limitation, its an iphone limitation, thus why it seems to work fine in the simulator.

As far as "Gold Dust", the programmers are, most likely, using straight C/C++ to code the animation as opposed to an interpreted language. Also, they're probably using purpose-specific code, as opposed to higher-level, general purpose routines like provided by Corona.

Having said that, I've made some tweaks to freshworks original code so it now runs at a steady 14+ fps (that's 8500 stars updated per second) on my 2nd Gen Touch, as opposed to the ~6fps of the original code... :)

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--- code start ---
display.setStatusBar( display.HiddenStatusBar )
local txt = display.newText( "", display.stageWidth/2, 8, nil, 10 )
txt:setTextColor( 255,0,255 )
local function init_fps()
        local fps_lst   = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}
        local fps_ndx   = 1
        local fps_tally = 0
        local prev_time = system.getTimer()
        return function( event )
                local etime = event.time - prev_time
                prev_time = event.time
                local cur_fps = 1000 / etime
                fps_tally = ((fps_tally + cur_fps) - fps_lst[fps_ndx])
                fps_lst[fps_ndx] = cur_fps
                fps_ndx = fps_ndx + 1
                if fps_ndx > 30 then fps_ndx = 1 end
                txt.text = string.format( "%2.2f", fps_tally / 30 )
        end
end
Runtime:addEventListener( "enterFrame", init_fps() )
local stars = {}
for i = 1, 600 do
        local star = {}
        star.object = display.newRect( math.random(320), math.random(480), 1, 1 )
        if i <= 200 then
                star.object:setFillColor( 100, 100, 100 )
                star.object.speed = 1
        elseif i <= 400 then
                star.object:setFillColor( 155, 155, 155 )
                star.object.speed = 2
        elseif i <= 600 then
                star.object:setFillColor( 255, 255, 255 )
                star.object.speed = 3
        end
        stars[i] = star
end
local function updateStars( event )
        local s = stars
        for i = 1, 600 do
                local o = s[i].object
                o.y = o.y + o.speed
                if o.y > 480 then o.y = 0 end
        end
end
Runtime:addEventListener( "enterFrame", updateStars )
--- code end ---

Also there's a bit of code that will compute the average FPS over the previous 30 frames.

(Still at the airport -- 2nd attempt at posting from Droid browser)

I just grabbed Gold Dust on iPhone, and it looks to me like an OpenGL hardware particle effect, as opposed to actually compositing thousands of sprites. I agree that it would be awesome to get access to some of this stuff via Corona :)

freshworks -- are your builds still not working on the device? Could this be the dreaded "8-character bug" in 1.0?

I actually tried it with images: an 8x8 & an 64x64 image, both with a single non-transparent pixel. Both where slower than just using newRect.