After attaching the profiling tool 'jProfiler' from ej-technologies to a CQ 5.x instance the instance doesn't start correctly anymore.
The log files contain error messages indicating that the jProfiller classes cannot be found when the OSGI bundles are activated. 

Resolution

In crx-quickstart/launchpad/sling.properties set the following property

sling.bootdelegation.com.jprofiler = com.jprofiler.*   This will also be stable for future extensions.

Applies to

CQ 5.3

CQ 5.4