Hello, I am an android developer and developing an Android mobile app. I notice an issue in my app that it takes around 5-6 secs from an activity back to the previous activity. I am using TraceView to trace the codes and the max used time is about 800msec for whole app. it seems that the cpu is not using that much time. The brief description about the issue is: in my app, MainTabActivity (extending TabActibity) has several tabs, choose a tab and display a list fragment, click an item to go to the item detail activity in which doing some add/delete functions. then click back key to the MainTabActivity. then choose another tab and show another list fragment, click an item to the detail activity, and then click back key. at this moment, it takes 5-6 seconds to go back to the MainTabActivity. in addition, click the option menu, it does not show the option menu (but If it does not take that long to go back, the option menu will show). Anyone can give me some idea how I can fix this? thanks alot.