Safari tab for maxes CPU

Discussion in 'Mac Apps and Mac App Store' started by frank4, Dec 15, 2011.

  1. frank4, Dec 15, 2011
    Last edited: Dec 16, 2011

    frank4 macrumors regular


    Oct 17, 2011
    Got a 1 month old Mini here, it works great so far. The only weird thing is when I'm using Safari and start a tab and try to go to, the following happens:

    1 - Safari Web Content process CPU goes to about 100% and stays there
    2 - as a result CPU temperature and fan speed rapidly rise
    3 - The tab does not display any content and just sits there
    4 - no significant changes in memory use, when the iCloud tab is started, lots of free ram

    I only let this go on a couple of minutes since it's obvious something is wrong. Then I delete the tab, and it goes away within a few seconds, but the Safari Web Content process continues running at about 100%. Then I quit Safari, and both the Safari and Safari Web Content processes go away within a few seconds.

    Problem occurs with both the stock 2GB ram and the 8GB ram I recently installed. I've disabled Safari extensions (ClickToFlash was the only one) and that doesn't make any difference.

    I have an iPad 2 that is set up to use iCloud mail and calendars, nothing else so far. I have a couple of Calendar notifications set up on the iPad and they get sent to the Mini OK, but that's the only iCloud activity I've done so far.

    Any ideas?

    Another clue: is only giving me this problem with my normal Mini user account, which is a "standard" user. Also a different standard user account on this Mini works correctly on And another account for "admin" on this Mini works OK. So there is something wrong with my normal Mini user account.
  2. frank4, Dec 18, 2011
    Last edited: Dec 18, 2011

    frank4 thread starter macrumors regular


    Oct 17, 2011
    I MAYBE found the source of the runaway CPU problem. It might be a bug in Safari, or the initially loaded webpage, for my particular configuration of Safari preferences.

    I had set up a stylesheet for Safari so it automatically zooms all web pages to 85%, the stylesheet is specified in the "advanced" settings preferences. That might be related to the runaway CPU 100%+ load in Safari Web Content on the page. There is no problem with other webpages since I first set up the 85% zoom stylesheet about a month ago.

    Here is what's in the stylesheet .css file:
    body {
    zoom: 85%;

    I've stopped using that stylesheet and Safari Web Content now shows less than 1% CPU but same memory used which I assume is normal and rather big, 234MB real, 321MB virtual with just 2 tabs open for MacRumors and iCloud, and cache emptied.

    As a test I tried using the stylesheet for 85% zoom again, and I expected the CPU runaway problem would come back. But now the tab works OK and there is no CPU 100% runaway. Very strange. Well maybe there is some hard to track down bug in, Safari, or the Safari Web Content process. In my research into this problem I noticed a lot of people have had recent problems with Lion's Safari Web Content using huge amounts of memory or CPU power, maybe that is the culprit.

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