-TED  Could you perhaps be a bit more specific? I do not mind constructive criticism -- indeed, I welcome it. However, blanket statements such as "I hate it" or "It's awful" do not help me improve anything. What would you do to make it better?

Are you referring to changes in 1.0.2 or the whole concept in general? In the former case, which change bothers you the most and why? I will probably add some preferences options at some point, and it would help me to know what you would like to be able to turn on and off.

I may be too busy for the next week or two to work on Convection, but I will continue to read all comments and take them into consideration.  
(Version 1.0.2)

TED  Hey, thanks for the heads-up on that threading problem! I think I have it fixed in an internal build, but I am adding some perspective effects to the screen saver and am not quite ready to post an update yet. It should be ready soon.  
(Version 1.0.1)

TED  Hi, it's the author again.

Are you referring to the jerkiness you see in Test mode when you run it straight out of the Screen Savers panel in System Preferences? I am not sure what is causing this, but the screen saver sometimes receives redraw events only sporadically in this mode. In 1.0.1, I moved the model computation into its own pre-emptive thread so that it is no longer affected by this sort of thing, but I am still at the mercy of the system as to when it lets me draw. I request 18 frames per second, but if I don't get them, I don't get them.

In my experience, when I run the screen saver for real, I notice it sometimes stalls for a moment within the first second or so, but then it carries on pretty smoothely. I have tested it on a 400 MHz iMac, an 867 MHz PowerBook G4, and a 1.8 GHz dual processor G5. If anything, I find it runs way too fast on the G5. It looks like I turned on a blender! Maybe I will add some logic to lower the time step on faster machines. The particles should then move about the same speed but flow more smoothely on the G5...in theory, at least. :-)  
(Version 1.0.1)

TED  Hi, this is the author.

Indeed, there is a definite problem when you run the screen saver in Test mode straight out of System Preferences. Everything turns white and the movement gets jerky. I have a theory about what is causing the former but not the latter. I plan to add some multi-threading to the model calculation once I figure out how to use NSThread. That may or may not help.

In the meantime, try running the screen saver the normal way (i.e. activate it with a hot corner or after a period of inactivity). I have run this on everything from a 400 MHz iMac to a G5 DP 1.8 GHz and it seems to work under regular usage.

Anyway, thanks for the feedback!  
(Version 1.0)

DOH!  And I'm betting you have a slow Mac. Had you bothered to check the developer's site, one click, and you'd be able to red that the developer states this is a CPU hog and not meant for slower Macs.

So you rate it poorly because your have a slow Mac? Yeah, that's fair, yeah right. Sheesh.  
(Version 1.0)

ANONYMOUS  Tried it on an eMac, iMac and iBook. They're all slow, and sometimes in white.  
(Version 1.0.1)