Apps are really slow opening on my brand new iMac any ideas ?

If by slow you mean Word is taking 15-20 seconds for the Document Gallery to appear (as an example) then your computer is pretty normal. (The first time a program is ever run it will often be much slower than the subsequent launches.) If slow means a minute or two for Word's gallery to appear that isn't normal.

If you didn't get the Fusion drive, you are launching programs from a hard drive spinning at 5400 RPM which is a slow hard drive. Your iPad is not only launching smaller applications but it is launching them from flash RAM which is way faster than a hard drive.

The warranty entitles you to complimentary phone support for the first 90 days of ownership.

If you bought the product in the U.S. directly from Apple (not from a reseller), you also have 14 days from the date of delivery in which to exchange or return it for a refund. In other countries, the return policy may be different. If you bought from a reseller, its return policy applies.

A brand new Mac will index its hard disk's contents for Spotlight search purposes. This takes some time away from its processor that would otherwise be available. Subsequent updates to its index have a negligible effect on performance.

If your brand new Mac still appears to perform slower than you expect after using it for an hour or two, contact AppleCare.

Goood point about the Spotlight index. After migrating apps and data I don't even want to think about how slow the computer would run with a 5400 RPM drive which indexing was going on.