Uninstall or Move Apps to Free Up Space
It's also worth mentioning that even if an app doesn't misbehave (heck, even if you don't run it at all), it can cause slowdowns on your device. Believe it or not, the more free space you have in your phone's internal memory, the faster your phone can write to the disk. If you aren't sure how much free space your phone has, you can check it by going to Settings > SD Card & Phone Storage to see. You can also see which ones are taking up the most space by going to Settings > Applications > Manage Applications, hitting Menu, and sorting them by size. If you find you aren't even using an app that's hogging space, you might as well uninstall it—no point in keeping it around just so it can slow down your phone.
Your other option is to use the ever-handy Apps2Sd to move some of those apps off your phone's internal storage and onto your SD card. By default, the developer of a given app usually decides whether an app will install to your SD card, but with the App 2 SD app, you can do it yourself. Just pop open the app, and you'll get a list of apps that are on your internal storage that have the ability to move to the SD card. Just move them over to free up space.
source : lifehacker.com