When I make some changes in source code, Android Studio (actually gradle) has to rebuild the project. It's clear.
Why the second build takes almost the same amount of time like the first build, even if I didn't make any changes in the project?
When I look into GradleConsole it waits on "assembleDubug" task. I think gradle should be aware there's no changes and shouldn't waste so much time on it.
Finally, I found the solution: turn on Offline work for gradle.
or using CLI:
./gradlew --offline assembleDebugOrWhatever