Since this version was first released/installed, I'll have times when a session hangs. I usually open new links in separate tabs. Sometimes they work - sometimes they just sit there. I'll see a spinning arrow/dot in that tab and nothing happens. My main tab is usually open to the Drudge Report, which refreshes every 2 minutes or so. When I notice the spinning arrow/dot in that tab is when I realize that something wrong. There is never that "not responding" message at the top of the browser, so those old problems I used to see (memory issues, etc) were resolved with this new design. And did not have this problem under 57. It's not an issue with my ISP, because at the same time Firefox is spinning its wheels, other browsers (such as Chrome) can load web sites. And I can also retrieve email with my desktop client. Then, after anywhere from two to five minutes, everything returns to functioning properly in Firefox. I'm currently now up to 58.0.2 with the same problems.