Believed to have you use iPhone or iPad mostly do this together because they think that to close it, it will not process any more like this can help save battery life and help the size of RAM empty but now it was clear that the like this or not do this smartphone in the normal process and no battery power saving.
According to sources, a number of foreign news released from the programs that we have already opened (Recent Apps) At Multitasking can save battery life, even if you close those programs or closed. Once you stop using them, you can come out homescreen or lock stops once these programs do not travel anymore, when you leave, so no need to close the program and those contacts.
To save battery power, this way you can, whenever they go to Settings> General> Background App Refresh after Disable it. Each time a user or application is using the program, it will not automatically process until drag to Refresh it shows recent updates, then you need to close the Recent apps and leave normal homescreen, so normal.