I was using two different Google map programs and switched to only yours today. That is not the cause just providing background.
Zooming and draging the map works for a short while then it locks up. I can get it to unlock by refreshing the browser. Browser this happens on are E, EI, Crome, Firefox. For what it is worth it seems to happen quickly if I zoom out
I even tried it on a non windows 10 computer just to see if it was a windows 10 issue. Web site is https://www.ghmail.us
One map is on the home page the second is Connect>Weekday & Off Campus Bible Studies
On the map with multi addresses sometime the markers just disappear. I was going to purchase the plugin for the additional capabilities but only if I can get it to work.
It is a test site for our church webpage.