iPhone 4s restart all 3 minutes , why ?

Have no idea what your question is.

You need to add a few more words to make your sentence complete and understandable.

If your iPhone takes 3 minutes to start (every time, more than just once) ... I would say there is something wrong. Try the usual restart, reboot, etc. things.

DFU is used within a jailbroken iPhone. that is not supported here.

Under the Terms of Use of this forum it is prohibited to discuss jail breaking. By jail breaking your iPhone you void any warranty you may have, forfeit any support from this forum, leave your iPhone vulnerable to malware and risk bricking your iPhone should you attempt future software updates or restoring your iPhone - http://support.apple.com/kb/HT3743.

How many GB is the device? I can tell you that the more information you have on it, the longer it will take. The device is not just turning itself on at this point, it is organizing files and starting all the services necessary to make your device run.

My 64GB iPhone 4S is about 3/4 of the way full at 52.8GB of info on it. . . Usually, it takes about 3-4 min to restart (slide to power off) from the time I slide until it is back on my home screen. A hard reset sometimes will take 2 minutes on a quick day.

{exactly why I don't do free help}

You have no idea what you are talking about. find an article on apple support internal or external knowledge base that shows anything that says DFU.

{exactly why I don't do free help}

I've worked for an AASP for over a decade. don't even go there.

Your info is Incorrect. DFU is a hacking method and not needed for anything other than hacking or occasionally fixing hacked phones. >90% of people who post about using "DFU" mode have no clue what it is and confuse it with Recovery Mode.

http://www.ihackintosh.com/2009/06/recovery-mode-and-dfu-mode/

"DFU Mode : DFU Mode is a special mode where the device can still interface with iTunes, yet it does not load the iBoot. The screen will appear totally black in DFU mode, so you can’t guess whether the device is in DFU or powered down from simply looking at the screen. Because iBoot and the OS are not loaded this exploit makes us able to downgrade your iPhone firmware or upgrade with a custom firmware created by Pwnage tool."

If no change after restoring the iPhone as a new iPhone or not from the backup, the iPhone has a hardware problem.