Speed Up iPhone 3G on iOS 4, Turn off Spotlight Search [How to Guide]

Well, Today a member in ModMyi has posted that he could find a way to speed up iPhone 3G on iOS 4 as he noticed a lot of people complaining about iOS 4 on iPhone 3G and it really kicks iPhone 3G speed! The way was very simple and easy, it's just about to turn off Spotlight Search, Check how to do that below..
Steps:
It's simple and easy, all what you have to do is to go "Settings" >> "General" >> "Home Button" >> "Spotlight Search", Now switch off all that in there to be the final screenshot like this,