Q: Safari Web Content high CPU usage

pjdm, thanks for the excellent suggestion.

I have a brand new Retina Macbook Pro, running Mavericks. It has 16GB RAM.

Whenever Safari is running, there is an instance of "Safari Web Content" that runs at 100%. If I quit Safari and open it again, the process comes back immediately.

With Safari doing this, I get only about three hours battery life - a far cry from the "all day" promised by Apple. If I quit Safari, then the battery meter will show over 8 hours on a full charge, even when running an intensive application like Aperture.

This has been the behaviour of this machine ever since I took it out of the shrink wrap just over a week ago.

OS X version 10.9

Safari version 7.0

I look forward to Apple issuing an update that fixes this issue.

Clear your reading list! See if it helps!!! There may be a download link or something in there!!

I had exactly the same issue!! 100% CPU on Safari Web Content. the site causing it was an oxford university Mirror hosting site.. I reset safari.. nothing.  I formatted my HDD and clean installed mavericks. opened safari with just my Apple ID registered... nothing changed! after a minute or 2 it was 100 % again.. spoke to many tech guys and nobody could figure out what it was!

I was sat at my mac this morning making another Install USB for mavericks and decided to clean up my bookmarks and reading list entries..

There it was!! An XBMC download link in my reading list!! Deleted it and PROBLEM IS SOLVED!!

This has done my head in for a few weeks! been using google chrome ever since! ive now deleted it and i hope this can help others figure out the issues with their own machines!!

Hope this helps you guys!!!

Stuart

Well, I checked, and I have zero items in my Reading List, so that's another dead-end for me. I'm so tired of Safari slowing, freezing, crashing, and since I updated to 10.1.10, the darn thing will reboot the Web Content all on it's own, even when I'm not experiencing any slowness, which is super frustating, as I'm often in the middle or writing stuff, and it just refreshes, losing everything I've just done. *** APPLE???  This is no way to program a browser, I have no problem with rebooting the Web Content MY SELF, when it gets too bogged down, and can't stand it doing this so arbitrarily and so often!

How would I set that up?

I have the same issue as many users here. Safari Web Content takes 100% CPU on a MacBook Pro Retina if Safari is running, even if I have no(!) browser window open. My Reading list is empty.

I have been experiencing the exact same problem very recently. MacBook Pro late 2009 updated to Mountain Lion and Safari 6.1 & 8GBytes of RAM, previously with no issues. I tried numerous suggestions above (all except re-installing OS X) and even just one tab would max CPU usage. Installed Chrome - no problems at all.

Decided to power cycle MacBook - not something I do very often at all - problem goes away on Safari now. Eleven tab on a single window and % usage around < 10% for Safari and Safari Web Content combined.

Now to see what triggers the rise in CPU usage. I run iStat Menus which puts a little CPU usage widget in the top bar so I don't have to keep looking at the Activity Monitor to spot any rise in CPU usage.

Will be fascinated to know what is causing this

I deleted the two items in my reading list - no improvement.

However, I think I have found a solution:

In the Privacy tab of Safari -> Preference, click the button to "Remove all website data". Accept all options to delete everything.

My Safari now behaves as expected, without running the CPU at 100%.

Cheers,

James.

It's obvious from the comments in this thread, that there are several different causes for this problem. Having tried several of the solutions mentioned above, it turned out that, for me, the problem - stuck on over 100% cpu, often on several Safari web process - was caused by Trusteer Rapport.

Rapport is a security app, offered by some banks.

The Rapport app itself used very little cpu, but seems to have interacted with Safari to cause the high cpu percentages. Once Rapport was removed the % has plummeted to almost nothing, and a day later it's still way down.

The easiest way to remove Rapport is to use the uninstall app, which can be downloaded from:

http://www.trusteer.com/support/uninstalling-rapport

Thanks for that CDAH, I just removed Rapport from my MBP (mid-2010) and can confirm that cpu usage dropped to almost zero. Ironically I am also running Rapport on my late 2009 iMac without any issues, so it wasn't something I even considered as a culprit.

My 2013 MacBook Air running Mavericks is acting up. Whenever I open Safari, "Safari Web Content" in Activity Monitor is either at or over 100% under CPU. I have no idea what to do.

If you have any items in your reading list, clear them. You might like to clear them one at a time, then quit and restart Safari to see which one is to blame.

If this doesn't work, try clearing all website data:

In the Privacy tab of Safari -> Preference, click the button to "Remove all website data". Accept all options to delete everything.

This worked for me, on a brand new 2013 MacBook Pro Retina.

Cheers,

James.

Cleaning website data looks promising for now.
THX 

I tried everything and none worked - UNTIL - I tried the Rapport deletion.

Webkit / Safari BEFORE removal - almost 100% usage

DELETE RAPPORT and restart Safari

Now - CPU usage minimal (istat menus only reports the top five processes and Safari . webkit does not list now)

I have the same problem (only realised my fan has been going crazy while leaving idle a couple of days ago). Safari Web Content (Not Responding) in red colour and eating up CPU usage.

However, found out that by cleaning up my recent Bookmark list solved the problem.

Somehow, my iphone created a bookmark folder with about 10 youtube links.

iCloud must have sync it to my MBP.

Deleted that bookmark folder on my MBP's Safari and fixed the problem right away.

Maybe you can try focus on your bookmark list that links you to site with video streaming for a start?

Hope this helps.