Speed up your iPhone - Here is how

1. Leave at least 500 MB of free space 
2. Do a soft reset (Hold both physical buttons until shuts off and reboots to Apple logo)
3. Download fewer emails (In Settings " Mail, Contacts, Calendars", Show 25 Recent Messages)
4. Clear your browsers history (In Settings "Safari", scroll all the way down, you will see "Clear History" in the list)
5. Clear your browsers cookies (In Settings "Safari ", scroll all the way down, you will see "Clear Cookies" in the list)
6. Clear  browsers cache (In Settings "Safari", scroll all the way down, you will see "Clear Cache" in the list)
7. Clear old SMS messages.
8. Reduce the number of Apps.
9.  Turn off radios you don't use (If you don't use Bluetooth and/or WiFi turn it off in "Settings")
10. Instead of constantly checking for new emails, change it to hourly or manually even (Turn off "Fetch New Data" under "Settings").