I created a custom feature as below. When install this custom feature, Fuse ESB container freezes on 'Refreshing bundles org.apache.servicemix.bundles.cglib'.

<features xmlns="http://karaf.apache.org/xmlns/features/v1.0.0">
  <feature name="test-feature" version="1.0.0">
    <bundle>mvn:org.apache.servicemix.bundles/org.apache.servicemix.bundles.cglib</bundle>
    <bundle>mvn:org.apache.servicemix.bundles/org.apache.servicemix.bundles.ant/1.7.0_3</bundle>
  </feature>
</features>

Note, I have a workaround applied on Fuse ESB container to workaround the problem described by this JIRA: http://fusesource.com/issues/browse/ENTESB-647.

Here is the workaround:
Open "etc/startup.properties" file and replace asm bundle to asm-all 4.0. So you need to comment out this line

#org/apache/servicemix/bundles/org.apache.servicemix.bundles.asm/3.3.1_1/org.apache.servicemix.bundles.asm-3.3.1_1.jar=20

and replace it with this line:

org/ow2/asm/asm-all/4.0/asm-all-4.0.jar=20

Then download the asm-all-4.0.jar from http://repo1.maven.org/maven2/org/ow2/asm/asm-all/4.0/asm-all-4.0.jar and copy it to your Fuse ESB 7.1 installation directory under "system/" folder with directory structure of "org/ow2/asm/asm-all/4.0/asm-all-4.0.jar". Then delete "data/" directory to start Fuse ESB 7.1 container fresh.

It looks like when the problem occurs, CPU also starts spinning.