Starting from CQ 5.6.1, the referencedBy property has been introduced in order to keep track of the pages that reference the same link.
However, in case a link such as external links in the page footers is referenced from too many pages, Linkchecker performs a lot of JCR writes/update causing CPU peaks as well as performance decreases, mainly caused by the JCR locks.
To verify if the repository growth is related to the linkchecker, enable TRACE log level for org.apache.jackrabbit.oak.jcr.operations.writes during a few minutes, and check if the majority of the writes are below /var/linkchecker. Then do not forgot to disable the TRACE log level.
In such cases where performance is compromised by this linkchecker behaviour, it is recommended to disable this feature by following the steps below:
1. Delete /var/linkchecker (it will be recreated automatically)
2. In the OSGI configuration console, open Day CQ Link Checker Info Storage Service and deselect "Save external link references” option and save.
Please note that, disabling this option will not cause automatic removal of the existing referencedBy property values. To achieve this, first remove /var/linkchecker.