problems with iPhone 4S 5.1.1

2 weeks ago i noticed that my iphone worked strange so i decided to update to the 5.1.1 ios,

after the update , the iphone started work worse than before..

the main problems are:

1. after 30 seconds that the screen is on Lock Screen, i push the Home / sleep botton and there is a delay of a couple seconds., (it didnt worked this way when i bought the phone)

2. when i touch to open an application , there is a Delay.. and its really annoing !

3. when i open Settings or Music , its open it slower than before..

4. when i play Asphalt6 or GTA3 it have lags and bugs,, (it didnt worked like that before) i saw on youtube that it dont have to work like that..

well , its really really ***** that my 2 monthes old iphone work pretty much like my old 3GS (even the 3GS didnt show problems like DELAY when i open app)

how can i solve these problems???

plz help me 😟