I'm a user of Docker plugin for Gradle, which relies on your library.

I've met a performance issue in my Gradle build (bmuschko/gradle-docker-plugin#88), but can also reproduce it calling your library directly.

My Dockerfile is minimal:

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

But a content of the directory is rather large: it's over 2000 files, 600 Mb in common.

Calling Docker build from a command line takes about 2-3 minutes, and produces 10-30% of CPU workload.

Running the same build using docker-java takes over 20 minutes, and loads CPU for 85-100%.

Here is a Groovy script which reproduces the issue: https://gist.github.com/mkuzmin/6d675411bf668e46d800#file-docker-java-groovy

An here is a stack dump:
https://gist.github.com/mkuzmin/6d675411bf668e46d800#file-groovy-stack-dump-txt

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