Lower the Number of Home Screens You Use And Ditch Those Widgets
If you have an HTC phone with the exclusive Sense UI and you'd rather not ditch it for something like LauncherPro, that's fine—you can still put this tip into practice. While some phones, like the Motorola Droid, come with a mere three five home screens, many (including most HTC phones) come with up to seven. While this is pretty handy if you like lots of icons and widgets (which I'll mention again in a moment), they can really take up a lot of memory on your phone, which can cause jerky animations, lag, and force closes.
In our guide to organizing your Android home screen, we mentioned the two philosophies behind home screen usage. It's fine to have lots of home screens, icons, and widgets, but if your phone isn't performing up to your standards, you may have to compromise and try using fewer home screens (or at least find a middle ground). I went down from seven to three home screens and haven't looked back—the jump in performance was pretty incredible.
If you're using LauncherPro, you can pick your number of home screens by hitting the Menu button on your phone, tapping Preferences, then tapping Homescreen Settings. If you're sticking with your stock launcher, you may not have the option to actually decrease the number of home screens, but you can still benefit by removing some icons and widgets from two to four of your home screens. It probably won't give you as big of a benefit as getting rid of the screens entirely, but those widgets can still suck up tons of memory, and deleting them from your home screen should make your phone run noticeably smoother.
source http://lifehacker.com/5709148/how-to-speed-up-your-old-sluggish-android-device