Since a couple of days I have problems with the CPU usage of my Safari installation. It runs on OS X Yosemite 10.10.4 (MacBook Pro 13" from 2011).

To reproduce it I only have to open one empty tab and do not need to interact with Safari. After a few seconds the CPU usage goes extremely up. Also the fan is mostly on full speed and the Laptop gets quite hot.

But within that situation if I would open new tabs and browse web content it would work without problems. But then when I want to close Safari it hangs. I can only close it by killing its process.

So I tried analyzing it a bit by having a look at the process:

enter image description here

Here it shows that Safari has 98.4% CPU and a quite huge CPU time of 30:13,03.

I then had a look on what happens inside the process by looking at the call graph, but I did not find anything suspicious (but to be honest I am not a C or Apple expert).

I found some similar articles about Safari CPU problems which are caused by the discoveryd process. But as far as I understood those problems are already solved with Yosemite 10.10.4.

Any ideas about how I could track down the problem and fix my Safari installation?

  • do you have any add ons for Safari ?
    – Ruskes
    Commented Jul 24, 2015 at 18:52
  • Disabling all extensions was the first thing that I tried. Without success. Commented Jul 24, 2015 at 18:54
  • OK, I did not know that. So I assume your tried deleting Cookies, Cache and extension data ?
    – Ruskes
    Commented Jul 24, 2015 at 19:04
  • Yes. First I deleted only the cookies and cache which did not work. Now I found a way to completely reset my Safari (see my answer). Commented Jul 24, 2015 at 19:09
  • Important to note here that that CPU percentage is the percentage of CPU time used, not available. You'd have to look at the system load to verify that Safari is indeed using undue processing resources Commented Jul 24, 2015 at 23:23

2 Answers 2


I found a way to reset my Safari installation this way:

1) I created a backup of my bookmarks:

cp ~/Library/Safari/Bookmarks.plist ~/Desktop/

2) I deleted some Safari specific files:

rm -rf ~/Library/Caches/com.apple.Safari \
       ~/Library/Caches/com.apple.Safari.SearchHelper \
       ~/Library/Caches/Metadata/Safari \
       ~/Library/Cookies/Cookies.binarycookies \
       ~/Library/Cookies/Cookies.plist \
       ~/Library/Preferences/com.apple.Safari.plist \
       ~/Library/Preferences/com.apple.Safari.Extensions.plist \
       ~/Library/Preferences/com.apple.Safari.LSSharedFileList.plist \
       ~/Library/Preferences/com.apple.Safari.RSS.plist \
       ~/Library/PubSub/Database \

3) Then I restored my bookmarks:

mkdir ~/Library/Safari && mv ~/Desktop/Bookmarks.plist ~/Library/Safari/Bookmarks.plist

Now the CPU and the fan stay calm.

  • 1
    nice work, a + from me :)
    – Ruskes
    Commented Jul 24, 2015 at 22:57
  • 1
    I tried multiple things. This one only worked for me. Commented Jan 21, 2016 at 8:04

Had same issue. I disabled plugins under safari preferences / security / plug inns , started up safari, problem gone. I quit safari, enabled the plug ins again , problem remains gone. Magic.

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