An Apple fan has outsmarted even the geniuses on the Genius Bar – with a trick which speeds up any iPhone without resetting it.
Unlock your device, so you can see the home screen, then hold down power until ‘Slide to Power Off’ appears. Now release it and hold down the Home button for five seconds.
Doing so refreshes your phone’s RAM – ie it clears out the working memory, killing off processes that might be slowing down your device.
Finder Marc Forrest says, ‘A few people have asked about the benefit, and from my understanding it clears the unused RAM on the phone. ‘I have done a number of tests to see if it works and I can promise it helps speed the phone up, a LOT!’ .. see more
source: metro UK