I'm working on an Android application with 3 Activities. 
They behave as three different tabs, so in its normal use, the user is likely to switch between one to another in a quick way.
To do that, I've always used the following code:

```
Intent intent= new Intent(currentclass.this, nextclass.class);
startActivity(intent);

```

However, at least two of the Activities may show a huge list of buttons viewed in a ScrollView View. By "huge" I mean 500 elements or so. Thus, as you can imagine, it takes too long to switch from one Activity to another one. Creating a new Activity every time instead of recovering an old one is mostly the problem.
Indeed, it is slightly faster to switch from some Activity to the previous visited Activity (which is the default backButton functionality) than to do it by the code above. I would like to know why exactly is it and how to benefit from it (using some flags on the Intent object).

Insomuch as even the backButton does not satisfy the performance I'm looking for, I would also like to hear about any suggestion which can improve my switching implementation.

Thank you!