You are mostly correct.  Any background program running can cause a delay.  But as Carbonite works continuously if it was only Carbonite you would have this problem throughout the day.  I have added tons of RAM and that has not solved the problem.  I see it mostly with QuickBooks Desktop, every once in a while ProSeries and my personal belief is that Intuit is just trying to piss me off more.  And yes, that's my technical answer.