How can we use existing selenium scripts (java) to get some end to end performance metrics (low load)

I am trying to leverage existing selenium automation scripts in java developed by Automation team to get some end to end performance metrics (total page load time etc) - very minimal load, in parallel to api load testing.

Please let me know what will be the most efficient way to do that. Also i am looking for making minimum changes to the selenium scripts because this will be an ongoing activity with each release and i am looking for to use functional scripts as it is with performance wrapper around it.

Your suggestions will be appreciated.

thank you!