Why does Premiere Pro 6 Generate Peak Files?
Peak file creation as well as creating alternate forms of various assets is perfectly normal background behavior for Premiere.  When you load new assets into a project, Premiere automatically starts a number of background processes to analyze the clip and make it easier for Premiere to do its job smoothly.

This should not cause any trouble and should not be a concern to you.  It is just the program functioning as it should.  It shouldn't cause any problems if you start working with it prior to completion of the work, but some functions may work more slowly or provide incomplete information while the processes are still going on.