WordPress site loading slow

My first suspicion would be related to this:
Name Servers:
jupiter.is.co.za [ 196.4.160.3 ]
titan.is.co.za [ 196.33.171.36 ]
demeter.is.co.za [ 196.26.5.8 ]
‘https://www.whois.com/whois/ampath.co.za’
It looks to me like you have a lot going on before visitors ever even reach your site.

However,
Relevant Dates:
Registration Date: 1998-11-12

If you have not cleaned and optimized your database in a while, maybe make a backup and then try ‘WP Clean Up’:
https://www.ads-software.com/plugins/search.php?q=WP+Clean+Up

no, I have aspx pages running seperately on the same server/domain and loads instantly:
https://www.ampath.co.za/vacancies/

I need to know if there is some tool I run in wordpress to see exactly what is causing the slow load ?

I see at least a few possibilities here:
https://www.ads-software.com/plugins/search.php?type=term&q=speed+test
https://www.ads-software.com/plugins/search.php?type=term&q=queries
https://www.ads-software.com/plugins/search.php?type=term&q=slow+query
https://www.ads-software.com/plugins/search.php?type=term&q=slow+queries
https://www.ads-software.com/plugins/search.php?type=term&q=cron

I’ve tried everything, deactivated all plugins, loaded a new theme, but still each page takes about 20 seconds to load.

Any help would be really appreciated ?