Do icons on the mac dock make the computer slower?

No. Running a lot of Dashboard widgets will, but not having icons in the Dock. Having said that – check to see if your Dock icons indicate an application is running by looking for a “light” under its icon. If it’s running and you don’t need it, quit the app.

I’m not quite sure I understand your question.
“make the computer slower” I think you are talking about programs that hog system resources and therefore other programs appear to run more slowly.
“icons on the mac dock” I think you are saying that the graphical (flowing, magnifying, cool-looking) icons are pretty but you are concerned about how much system resources they consume.
Well, certainly the pretty dock does take some resources. You can turn off some of the dock features (like magnification) and that will lessen the load. Further, you don’t have to use the dock at all—you could just launch icons from your Desktop.
I am curious about which Mac hardware you are using. On “modern” Mac hardware the overhead of the dock is not noticeable (in my humble experience) and well-worth the convenience and the cool-factor.
I hope you enjoy your Mac as much as I have!

oh yes i enjoy my mac a lot “arglebargle”. and what i mean is does it hog system resources. because i consider myself pretty smart when it comes to macs, and i was looking at my coachs macbook, and i asked why he had only 4 apps in his dock if he used more than that. and he said because having lots of icons down there (not open ones, just ones sitting there) hogs the resources and makes the computer run slower, and i argued with him for about 15 minutes and wanted to know if I was right because i was pretty sure that it didnt effect performance, and if so it was not noticeable

I agree with PupnTaco. In general I see more problems with Widgets hogging resources.
So you question whether the number of icons displayed in the dock would have a significant impact on performance.
I would say that I don’t think so, unless you are running a modern version of OSX on older hardware (in this situation all system resources may be strained and then you would be more likely to notice the dock).
Off the cuff, I think it is unlikely that the number of icons will make any difference.
That is just an opinion and I would love for someone to prove me wrong.

I wouldn’t worry about it.

However, Having lots of stuff on your desktop will slow stuff down.

@ JP: Browsing vintage girly magazines would slow me down for the whole day!

@koesac: Having stuff on your Desktop will not slow you down. Filling up your hard drive so there isn’t any scratch disk available for virtual memory will slow down the computer and can be fatal to the OS, but simply having things on your Desktop does nothing to performance in and of itself. It’s just another folder, essentially.

@PupnTaco: I read that here, but maybe it is not true, have a look for yourself and tell me what you think….

”Every folder you keep on your desktop is treated like an open Finder window.”

I don’t know how correct it is, there is some question about it in the comments, but I tend to find most of the stuff I read on that site is pretty good. There are also some other useful things in that article too.

I’m here to tell that’s BS. :)

Open windows are treated like open windows.

I skimmed the article and it may be confusion amongst
how fast the Finder runs
how fast the Finder “boots” (what is appropriate Macspeak?)

I read article to say that loaded Desktops did not slow the Finder (and cited evidence) but admitted that it took longer for the Desktop to startup (immediately after logging in).

this agrees with my meager experience.

I would agree with you Arg IV that sounds perfect.

anytime a misunderstanding can be brought to light—perfection is realized in some small measure
(blush)