I'm creating a Docker image by copying files without running any commands inside a container:

FROM java:jre
ADD server/TeamCity/ /opt/teamcity-server/

The layer is rather large - it's 2000 files, over 600 Mb.

Running a build by Docker takes about 3 minutes.
Running the same build by the Gradle task takes 40 minutes, and loads CPU for 100%.

Here is a stack dump.

I'm using:
Ubuntu 14.04
OpenJDK 1.7.0_79
Gradle 2.5
plugin 2.5
Docker 1.7.1