As we’ve previously reported, a variety of factors can cause Safari for Mac OS X to slowly load pages, open new tabs and windows, and perform other operations.
Apple has now posted a knowledge base article titled “Safari 5.0.1 or later: Slow or partial webpage loading, or webpage cannot be found,” which lists two potential fixes for the issue.
The first echoes our previously posted fix for the issue, switching DNS servers from those generated by your ISP to those offered by OpenDNS. To do so:
- Open System Preferences and click “Network”
- Select your connection method (AirPort, Ethernet, etc.)
- Enter the following items in the “DNS Server” field: 220.127.116.11, 18.104.22.168
- Click Apply
Or you can try Google’s public DNS servers: 22.214.171.124 and 126.96.36.199.
Apple’s second fix involves disabling DNS prefetching. We previously noted that anecdotal evidence suggests that this issue is caused by a problem with Safari 5.0′s DNS prefetching mechanism, which appears to send more requests than allowed by some ISPs. This issue may also cause problems with some routers.
Apple’s instructions for disabling prefetching in Mac OS X require opening the Terminal (click the Spotlight icon–magnifying glass–in the upper-right portion of the screen and type “Terminal”) then entering the following command:
defaults write com.apple.safari WebKitDNSPrefetchingEnabled -boolean false
then quitting and restarting Safari.
Apple also recommends upgrading router firmware or switching routers, and offers instructions for re-enabling DNS prefetching if a firmware update or router switch resolves the issue.
For full instructions, including prefetching disabling instructions for Windows, and re-enabling prefetching, see the knowledge base article.