I use Safari on my MacBook Pro. I usually get the “This website is using significant memory” message every day after I’ve been using it a while and looking at big list of observations or doing a lot of searching with the map. For example, when I try to identify things for others and when I scroll thru my own observations (close to 1000) . It’s a pain but i usually find a good stopping point and close Safari and then relaunch it.