what is Android Studio Instant Run?

Instant Run = Incremental build + Hot, Warm, or Cold swap

Without Instant run :

With instant run :

Source : https://medium.com/google-developers/instant-run-how-does-it-work-294a1633367f

Instant run comes with the latest version of Android Studio. But in some cases it is wired when using that.

What is Instant Run?

In an ordinary build and run the whole APK file is updated and pushed to the device. But when using instant run only the updated part gets replaced in the device. Instant Run pushes updated code and resources to your connected device or emulator by performing a hot swap, warm swap, or cold swap. It automatically determines the type of swap to perform based on the type of change you made.

Pros

It may be faster than an ordinary build. But it requires the application to be running at the time of build below API 21.

Cons

Seriously I felt a problem of the unchanged installation. That is when using instant run at some times the application seems to not updating. It is staying at its previous build. And sometimes I felt it was slower than an ordinary build.

Hot swap:

This is the fastest type of swap and makes changes visible much more quickly. Your application keeps running and a stub method with the new implementation is used the next time the method is called.

Warm Swap:

This swap is still very fast, but Instant Run must restart the current activity when it pushes the changed resources to your app.

Cold swap (API level 21 or higher):

This swap is a bit slower because, although a new APK file is not required, Instant Run must restart the whole app when it pushes structural code changes.

Disabling instant run: File=>Settings=>Build,Execution and deployment=>Instant Run=>Uncheck enable instant run for hot swap

See this documentation.

Instant run:

It’s a feature in Android Studio that uses magic to significantly reduce the build and deploy times for incremental code changes during your coding/testing/debugging lifecycle.

This is normal and is part of the Instant Run feature. In theory, subsequent loads should be faster.

You should try re-enabling it and observe for the subsequent runs, you will see the results.