About this question there are many answers but we present you the best way among all just follow the ideas given below:
Just turn off the spotlight search...
If you don't know how to do it then follow these steps:
1)go to settings
2)click to general
3)see spotlight there...go there
4)uncheck all ticked one...
By this your iPhone will be little fast
The best way to do it is to downgrade to the original version again..but remember doing this will loose you some function such as multitasking,making folders,loosing some app to run over it,often app crashing,high frimware warning if 6.x.x firmware,....be careful you will be loosingsome basic functions that was on 4.x version...
We have got many ideas but we will be testing and giving you the information on that...we are on work...wait for few days