Learning how to use New Relic will help you understand where your code is not running optimally.
Monitor exactly which parts of your application are running slowly.
If you are new to New Relic, read: https://newrelic.com/application-monitoring
Highly recommend listening to @stanford ECorner podcast "Life is Too Short for Bad Software" featuring. Lew Cirne @sweetlew founder of @newrelic https://ecorner.stanford.edu/authorMaterialInfo.html?mid=3367