Slow or partial webpage loading

Symptoms

When loading webpages in Safari 5.0.1 or later, you may experience the following:

  • Slow performance
  • Partially-loaded pages
  • Webpage “cannot be found” message

Resolution

Your DNS server(s) or your router may be affected by DNS prefetching in Safari 5.0.1 or later.

First, try a different DNS service

Try a different DNS service, such as one of the DNS services below. This will test to see if the root cause of your issue lies with your selected DNS servers.

For information about how to change DNS settings in Mac OS X, see Editing DNS and search domain settings.

If the issue persists in Safari, return to your original DNS server settings if desired, then continue with the next section.

If the issue persists, disable DNS prefetching

Choose your operating system below to learn how to disable DNS prefetching.

Mac OS X steps to disable DNS prefetching

  1. Open Terminal (in /Applications/Utilities).
  2. Execute the Terminal command below to disable DNS prefetching:
    defaults write com.apple.safari WebKitDNSPrefetchingEnabled -boolean false
  3. Quit Safari, then open it again and test for the issue.

Microsoft Windows XP, Vista, or Windows 7 (32-bit) steps to disable DNS prefetching

  1. Open the Command Prompt (Choose Windows > Run).
  2. Execute the Command Prompt command below to disable DNS prefetching (include quotes):
    “Program FilesCommon FilesAppleApple Application Supportdefaults.exe” 
    write com.apple.safari WebKitDNSPrefetchingEnabled -boolean false
  3. Quit Safari, then open it again and test for the issue.

Microsoft Windows XP, Vista, or Windows 7 (64-bit) steps to disable DNS prefetching

  1. Open the Command Prompt (Choose Windows > Run).
  2. Execute the Command Prompt command below to disable DNS prefetching (include quotes):
    “Program Files (x86)Common FilesAppleApple Application Supportdefaults.exe” 
    write com.apple.safari WebKitDNSPrefetchingEnabled -boolean false
  3. Quit Safari, then open it again and test for the issue.

If disabling DNS prefetching resolves the issue, your router may be the root cause. Consider one of these options:

  • Keep DNS prefetching disabled.
  • See if your router has a firmware upgrade available that might address this issue. Contact your router’s support staff or visit its website for more information about how to obtain and install router firmware updates.
  • Upgrade to a more modern and robust router.

Enable DNS prefetching if the issue persists, or after upgrading your router/firmware.

Steps to re-enable DNS prefetching in Mac OS X

  1. Open Terminal (in /Applications/Utilities).
  2. Execute the Terminal command below to re-enable DNS prefetching:
    defaults delete com.apple.safari WebKitDNSPrefetchingEnabled

Steps to re-enable DNS prefetching in Windows XP, Vista, and 7 (32-bit)

  1. Open the Command Prompt (Choose Windows > Run).
  2. Execute the Command Prompt command below to re-enable DNS prefetching (include quotes):
    “Program FilesCommon FilesAppleApple Application Supportdefaults.exe” 
    delete com.apple.safari WebKitDNSPrefetchingEnabled

Steps to re-enable DNS prefetching in Windows XP, Vista, and 7 (64-bit)

  1. Open the Command Prompt (Choose Windows > Run).
  2. Execute the Command Prompt command below to reenable DNS prefetching (include quotes):
    “Program Files (x86)Common FilesAppleApple Application Supportdefaults.exe” 
    delete com.apple.safari WebKitDNSPrefetchingEnabled