Boot time when turning on imac

It seems that when I first bought my imac it would load OS X quicly -- maybe 15 seconds from turning on the machine to getting the desktop. Now I've noticed it takes longer -- up to half a minute, and that time from power on to desktop can vary sometimes.

I've also notices that the icons on the desktop and in the folders aren't (and I don't know the right work for this, so forgive me if it's not clear) fully or quickly 'displayed' -- for example, when I first click on the finder icon, if I click on the applications folder there's a lag -- I'll see a blank folder for a moment and then the application icons appear, with size of the applications being filled in one by one, down the list. I also have a Neoffice .xls file on the desktop, and after power on I notice the icon first has a green color to it, then changes to the standard white color icon.

Is there a problem here, or is it just that as I've added files, etc, that it's the normal consequence of more info on the machine? Is there any software out there that is the Mac equivalent of disk cleanup/defragment that can get my imac up and running as fast as possible? I don't know if I'm nitpicking, but it would be nice to give a tune up or something.

Open up a terminal window

type

sudo periodic daily weekly monthly

this will run the cleanup scripts that normally run if you leave the machine on all the time. Also check your login items and see if you've got a bunch starting. Defrag is not needed in hfs+ unless you've used up the vast majority of your disk space.

thanks Dysfunctional, ill try this when i get home later. My Macbook tends to take about 45 secs to boot, were a few month ago it only took about 29-32 secs, even tho i havent installed any apps.