Hello M,
Hope you are doing well!
Do you see any significant difference in loading time when the Custom Sidebar is hidden and shown?
Please note that, the plugin is a huge a plugin so it will take some memory. How much memory is take in your site?
Do you see same results when all other plugins are deactivated?
I would like to quote one of my coallegue Ash here:
Regarding P3 plugin
The ‘Autoscan’ feature will always scan your site as logged-in user (typically Admin) and also scan the admin pages. To get a more reliable perspective on the visitor experience click the ‘Manual scan’ button, then open another window and open some pages of your websites front-end as normal visitor. While Manual scan is enabled, P3 will profile all these pages you open in the second window. When you’re done finish the test in the first window and view the results…
Let us know how it went!
Cheers,
Nastia