If it's new from the shop, I assume you've got OSX Mavericks? I've no direct experience of mavericks, but on all my macs theres an option to make the keyboard respond slowly.
Try going to system preferences (in the dock), and then select the 'universal access' sub-menu, and then the tab that says 'keyboard'. If it's similar to OSX 10.6, which is what I'm using, there will be an on/off option for slow keyboard response.