first step is to install this plugin "query monitor"
refer this tip to know which plugin is actually putting load on your server :
https://kinsta.com/blog/query-monitor/
Using caching techniques like memcached, opcache on server side might improve some speed .
Also try switching to php version 7.0 (not 7.1 ,its unstable and is not compatible with theme ) .
Also follow this caching tip :
https://vibethemes.com/documentation/wplms/knowledge-base/wplms-with-w3-total-cache/
Deactivate plugins that you dont feel necessary
Please also try disabling touch points if you have enabled them from wp-admin -> lms -> setitngs -> touch points .