Ask Different is a question and answer site for power users of Apple hardware and software. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I usually have several tabs open in Safari in the background, and sometimes I see it taking up an unusual amount of CPU (PluginProcess or WebProcess).

How can I figure out which tab (or tabs) is causing this? If there are no easy GUI solutions, I'm also open to Terminal-based techniques for finding the culprit. I hope not to have to do this very often.

(Note: I realize this is similar to an old question, but Safari has been updated since then and perhaps there are new techniques available.)

share|improve this question
did you find a solution for yourself in the meantime? I'm having the same problem, but mainly for excessive use of RAM which seems to be triggered by some few tabs: – MostlyHarmless Mar 23 '14 at 11:44
@MostlyHarmless check out the answer below: @ jtbandes: please mark the mentioned answer as correct, as the one you marked, doesn't contain any solution – Ichixgo Feb 8 at 23:54
@Ichixgo: Thanks, as I am still using OS 10.6.8, I can not use Safari 6.1 – MostlyHarmless Feb 9 at 10:43
@MostlyHarmless: Too bad, maybe you wanna check out Chrome. It still runs on 10.6 and you can also check which tabs are hogging your CPU. Window > Taskmanager from the drop down menu. – Ichixgo Feb 11 at 0:16
up vote 11 down vote accepted
  1. You need Safari 6.1 or newer

  2. Enable Debug menu

    defaults write IncludeInternalDebugMenu -bool true
  3. Set "Use Per-tab web processes" and "Show Web process IDs in page titles" to on.


share|improve this answer
Good use of graphics – CousinCocaine Apr 10 '14 at 12:15
In modern Safari there's no good way to actually see these process IDs since the page title is almost always truncated in the UI, but this Safari extension can generate a list of all tabs including their full, PID-carrying titles: – Brent Royal-Gordon May 16 at 0:27

For what it’s worth, I’ve checked both the Develop menu and the Debug menu in the latest (Version 5.1.4 / 7534.54.16), and couldn’t find any helpful features.

Develop menu:

Debug menu:

The debug menu can be enabled using the following command:

defaults write IncludeInternalDebugMenu -bool true
share|improve this answer

cmd ⌘+alt ⌥+AWindow > Activity may help you to identify which tab is the heaviest in activity if it is lasting long enough.

I must admit that all my tests where failure, but I'm mostly using web servers which are fast.

I also tested Debug > Show Frame Rate Meter (see Mathias Debug dropdown menu) which is a partial answer to the original question. You have to test it by reloading every tab and compare the output of the 3 meters to see who is the hog.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.