Why does compilation take longer in Play 2.3.4 (activator) versus Play 2.2.4 (play)?

Scenario 1:

Start playing the 2.2.4 project with the command play ~run

, then move the code from A.java to B.java => the following output:

[info] Compiling 2 Java sources to D:\MyProject\target\scala-2.10\classes... [info] Compiling 1 Java source to D:\MyProject\target\scala-2.10\classes... [warn] Note: D:\MyProject\app\controllers\AdminController.java uses or overrides a deprec ated API. [warn] Note: Recompile with -Xlint:deprecation for details. [success] Compiled in 4s

Scenario 2:

Start game 2.3.4 (activator) with the command activator ~run

, then move the code from A.java to B.java => the following output:

[info] Compiling 9 Scala sources and 368 Java sources to D:\MyProject\target\scala-2.11\c lasses... [warn] Note: Some input files use or override a deprecated API. [warn] Note: Recompile with -Xlint:deprecation for details. [success] Compiled in 64s

Why does Play 2.3.4 recompile all sources in the second case? Are there settings for this? Both scenarios are designed for a single project, and in both cases, I ran play/activator clean

, and play/activator compile

before making any changes.