Safari taking 100% of one CPU - and the web page is taking most of another
I had an issue with Safari stalling with pages taking forever to load. I checked the Activity Monitor and both Safari processes (one tab) were at >100% CPU. I checked the activity in Developer Tool and it appears that the Google JS files were taking >5s each to load. As they were related to ads I removed my AdBlocker extension. Then the problem went away. makes me wonder if thisis something Google is causing or AdBlocker as it was working fine up to a week ago.
MacBook Pro 15", macOS 10.14