I know I’m not the first one to wonder this.
In short, when you have multiple tabs/pages open in the new Safari 7 (shipped with Mavericks), each one is now launched as a separate system process. This provides enhanced stability and security, as a runaway or buggy page won’t bring the entire browser to a halt or cause it to crash. You can view the list of processes in Activity Monitor, but it would be far more helpful for troubleshooting a runaway or hanging page that’s sucking up RAM or CPU cycles if you could identify the underlying page or URL of each process.
Chrome makes this possible with the Task Manager.
Here’s how to do it with Safari:
Mouse over the name of each process in Activity Monitor.
Simple enough, right? It’s not perfect. It looks like there might be two pages running under a single process occasionally. And you don’t see the full URL, only the top level domain. That’s not such a big deal unless you have a page on the same site open in more than one tab or window.
Haven’t seen this covered elsewhere. Just now randomly discovered the mouseover trick on my own, but contributor markhunte had actually mentioned it shortly after I started this stackexchange thread (for which I never received a follow-up notification. Thanks, Mark.)
There’s also a second, slightly more wonky tip that involves exposing the Process ID in Safari’s Title bar for each page that you can then match up to the PID column in Activity Monitor. It’s not all that much more helpful than the simple mouseover other than in above-mentioned case with multiple pages open from the same site.
Take your pick.
Either way, very welcome functionality. On its own, the separating of processes was a huge improvement. Until now, whenever I’ve noticed a runaway Safari 7 Web Content process, I’ve just resorted to blindly issuing a ‘force kill’ from within Activity Monitor. All that did was re-spawn the offending process, but it did fix things temporarily. Now, you can actually be aware of the offending process in advance and act accordingly, whether it’s keeping that tab closed until you need it, saving any work on the page if it’s no longer responding, etc.
Very exciting and long overdue.