• Leave free space. Leaving around 750MB of free space allows the iPhone to create more virtual memory.
• Less Email! Email downloading in the background is the number one cause of my iPhone slowness. Under settings you’ll be able to show less recent message.
• Get email less often. Uhh, What? It makes sense in terms of performance, but not to the email enthusiast. Checking for mail every 5 minutes will slow down your phone’s performance. Try using something longer – hourly or manually will greatly improve the performance of your phone for you email junkies.
• Delete old text messages (SMS).
• Apps Apps Apps! The more apps = the more screen rendering. Remove your unused apps.
• Clear Safari’s cache. You can do so under settings > safari > clear cache.
• Turn off Bluetooth and or WiFi. This can also help improve battery performance.
• If all else fails, try doing a reboot. Hold both buttons for a few seconds.