WP too slow

1) disable ALL plugins
2) temporally swap to the twenty-fifteen theme and test
3) reduce the number of post per page to 1

if none of this helps, then it might be an issue with your host. Some hosts throttle site activity depending n how much you pay for hosting. You could contact yout host and see if they can explain why your sites are so slow.

I would advise you to check out this thread. https://wordpress.org/support/topic/wp-site-takes-9-seconds-to-load-please-assist?replies=7 It includes some helpful information of how to speed up things.