Last month I wrote about multitasking and recommended that you try and avoid it to be more efficient.  Here's some additional information from an article in the Business Courier, written by Jon Newberry.  

"Research indicates that juggling too many things at once is counter productive.  [ ]  In a recent book co-written by Douglas Merrill, Google's former chief information officer, he blames the failure of multitasking on the nature of short-term memory.  It can only handle a few things at one time.  So when people switch tasks, their brains upload the information in their short-term memories into long-term memory to make room for the new activity.  That takes time and also introduces the opportunity for errors and lost information.  And when they later switch back to the original task, they have to go through the same process in reverse.  That's more time and more chances for error.  To minimize the cost of task switching, Merrill, who has a doctorate in psychology and cognitive sciences, recommends grouping similar tasks and doing them at around the same time.  That way many of the overlapping details don't have to be uploaded and downloaded too many times."