In order to know it, identify the day before the start of the traffic drop in Google search console or Google analytics. Here we can see a Google traffic drop on the 18th of September 2017.
1. Take a look at the date of your WordPress plugins
Open your favorite FTP application and go to the “/wp-content/plugins” folder. Sort the folders by date just like on the picture below. As you can see below, a WordPress plugin has been installed on this very same day (18th of september). It was the wp fastest cache plugin. We decided to delete it right away.
2. Other plugins prior to the traffic drop
Then, I took a look at the plugins that have been installed just before the date of the Google traffic drop. That’s the ones that you should disable in priority. This technique will prevent you to disable all WordPress plugins.
3. Some plugins don’t change your website code
Take a look at the remaining installations, several WordPress plugins have no consequences on your webpage’s code. Here, on the picture above, it is the case of “search and replace” and also “broken link checker”.
4. Take a look at the WordPress plugins that have been modified
Some WordPress plugins installed before the traffic dropped may have been modified. It would important to investigate the modifications. In my case, there were no significant modifications done.