Heavy development for apps comes with heavy usage. And when it comes to iOS, it is known that it has the most number of apps available for consumer market, when comparing with different platforms, i.e Android, Blackberry and Windows Phone 7. Performance does go down when a number of apps are installed which eat up a lot of power in any case.
Speed Intensifier is a tweak available for your iPhone which will make the hardware perform better with a speed boost. It comes in as two packages, for Settings and Winterboard. Settings tweak gives you access to reduce transitions / animations. Winterboard allows you to control your CPU’s speed.
Speed Intensifier tweaks (Settings and Winterboard) are available from Cydia.
via: iPhone Download Blog