Restore the 3g Ipone as a new phone will fix the slow problem

Did some try to restore the phone as a new one and fix the problema of the slow soft that the upgrade to OS4 cause ?

i tried everything to fix THE BRICK THAT APPLE MADE OF MY PHONE AFTER the the upgrade to 0s4, with no solution.

So now, before restore the iphone as a new one, i would like to know if someone saw any improve ?

Please, in the answer be sure to describe if the improve was only for the first day o permanet ?

Waiting for reply, thanks