Website slower because of plugin

I installed the plugin and it works fine. But my website has been a bit slow since I installed the plugin, I checked out why and I found a file coming from your plugin making my website slow. This is the name of the file: https://abctravel.nl/wp-admin/admin-ajax.php?action=ylc_ajax_callback&mode=get_token

Do you have any idea what this is, and how to fix this?