iCloud and the iPad

I have an iPad 2, an iMac and a MacBook pro. The iMac and the MacBook Pro are both hardwired into my router and the iPad is connected via WiFi to the same router. I use iCloud to synchronise my address book, calendar and reminders. If I make an alteration to any of these the iPad doesn't appear to work in the same way as the others. For example if I make an alteration on the iMac or the MacBook Pro, the other is updated as soon as I open the relevant App. The iPad however is not updated until several hours later. The same the other way round, alterations on the iPad take for ever to appear on the iMac or MacBook Pro.

Is there something I am not setting up correctly?

ElBeardo