If your iPhone becomes slow or seems to 'stutter' a bit as you try to open another app, here are two articles on how to quickly clear the memory on an iPhone and improve performance. Both articles tell the same story -- just in a different manner. http://www.iphonetricks.org/trick-to-instantly-clear-iphone-ram-memory/
http://www.cultofmac.com/399976/how-to-make-your-iphone-run-better-in-10-seconds/
Jim Hamm