Often times a new iMac will run slowly because Spotlight is indexing the entire hard disk in the background. Once the Spotlight index is completed, the computer will spring back to life.
If this isn't the case in your situation, please let us know. In the event it continues to run slowly, some questions for you:
- Have you added any software to your new iMac that could account for the slowdown? (e.g. anti-virus software).
- Is it slow in all situations, or only when you're doing something in particular?
- Is this your first iMac, or did you transfer data from an older computer?
- Does Activity Monitor provide any clues as to why your system is slow? (Activity Monitor can be found by going to Applications --> Utilities --> Activity Monitor).
I hope this helps.
Shutdown and restart it a couple of times and see if that improves things. BTW, AFAIK, indexing shouldn't slow things down. Click on the upper, right-hand, magnifying glass icon and you'll see what state the indexing is in. If the issue continues, contact Apple's Express Lane and let them deal with it, since it's a new machine.27" i7 iMac SL, Lion, OS X Mountain Lion (10.8.2), G4 450 MP w/Leopard, 9.2.2