Safari's "Use Per-Tab Web Process" Option

I only just discovered that the current version of Safari (v6.1) under Mountain Lion includes the "Use Per-Tab Web Process" option that is enabled by default under Mavericks. You need to enable the Debug menu (instructions here) and it's the option at the top.

What I'm curious to know is whether anyone has been running Safari with this option enabled for any length of time?

Personally ever since the update to v6.1 I've found Safari to be very unresponsive, with webprocess frequently leaping to 100% CPU usage and causing all tabs to stop responding, so I'm hoping a process per tab may alleviate this issue, even if it doesn't run quite as well as it does under Mavericks (thanks to App Nap and other features).

Of course the feature may also introduce instability, but I've only just enabled it so I can't really say. I'm going to give it a try for a while and add my findings.

 

Okay, since making my first post I've been using Safari just like I normally would, and things seem perfectly stable; well, at least I haven't encountered any issues I didn't get before. Instead I've actually solved the frequent lockups I got when opening lots of tabs, and while a bunch of processes are opened (as you'd expect) I don't notice much extra RAM or CPU usage.

So as far as I can tell, this feature has negligible overhead, but seems to make Safari more responsive. So I have to wonder why this feature isn't enabled by default under Mountain Lion.

Before enabling this, Safari 6.1 had been nothing but a step back from the previous version due to the frequent lock-ups and other performance issues, now it actually feels like an improvement (more like the Mavericks version).