long period of inactivity after closing application

[ThePuiu]

I wrote an application that the main activity through three buttons open additional 3 secondary activities. Each of these contains a relatively large number of images (not very large in size but many in number). To opening activities I do:

StartActivity(CompX)

but to go back to the main activity use the Back button. The application works fine on the phone, the problem occurs only when the main activity button for closing the application is pressed. The application closes but the phone does not respond to commands about 5-10 seconds, then recovers. Home key is only functional. If you press it, the phone is back to normal quickly.
My question is: is this approach correct (without closing programmaticaly secactivity)? It releases memory to pressing the Back? I chose not to use a button closure for reasons of design...
If you need further details are available! Thank you!

 

[Erel]

How are you closing the main activity?

 

[ThePuiu]

Sub ImageViewExit_LongClick
Activity.Finish
ExitApplication
End Sub

 

[Erel]

In most cases ExitApplication should not be used.

Remove it and your program will close fine.

 

[ThePuiu]

now it's working like a charm!
In rest, its ok to leave an activity without a close?
Thank you!

 

[Erel]

Calling Activity.Finish closes the current activity.

ExitApplication kills the process. It is better to let the OS handle the processes and kill it when it decides to.