Lagging in my keyboard
when I write my iPhone is lagging, needs 5 seconds to watch my sentence .. So how can I fix that?
ios 8 is a big mistake!!!
iPhone 5s, iOS 8.1.3
Try to reset the phone by holding the sleep and home button for about 10sec, until the Apple logo comes back again. You will not lose any data by resetting, but it can cure some glitches.
If this does not help, setting it up as new device would be the next step:
How to erase your iOS device and then set it up as a new device or restore it from backups