Submit Hint Search The Forums LinksStatsPollsHeadlinesRSS
14,000 hints and counting!

10.4: Turn off PAC to avoid Safari performance problems Web Browsers
Tiger only hintWhile Safari supports using a PAC File URL, enabling this feature on Tiger may cause performance problems, not just for Safari, but for everybody who uses your PAC server.

Turning on the "PAC File URL" in Safari may cause problems browsing, including broken images. The issue is that Safari doesn't cache the PAC, but instead requests a fresh copy for each object downloaded per page. Details on this problem (and some workarounds) are available via Full-Disclosure.
    •    
  • Currently 1.00 / 5
  • 1
  • 2
  • 3
  • 4
  • 5
  (1 vote cast)
 
[15,061 views]  

10.4: Turn off PAC to avoid Safari performance problems | 6 comments | Create New Account
Click here to return to the '10.4: Turn off PAC to avoid Safari performance problems' hint
The following comments are owned by whoever posted them. This site is not responsible for what they say.
Anyone seen similar issues with Firefox?
Authored by: silas on Jul 05, '05 01:45:25PM
Perhaps unrelated, I have performance problems using PAC with Firefox. I use automatic proxy configuration as detailed in this weblog entry. When I tell Firefox to use that PAC file, it becomes noticably slower for all sites, whether they're loaded through the proxy or not. So far I've traced it to repeated and perhaps broken DNS lookups of the IP addresses being checked in the "myIpAddress" javascript-ish call. I haven't pursued this with the Mozilla folks yet, but I thought I'd see if anyone tuning in to this article has experienced the same.

Silas

[ Reply to This | # ]

Anyone seen similar issues with Firefox?
Authored by: Rastor9 on Oct 11, '05 02:11:08PM

Firefox has its own proxy configuration settings in preferences. Add your proxy file location (same as in network configuraiton). This will clear up your Firefox issue.



[ Reply to This | # ]
10.4: Turn off PAC to avoid Safari performance problems
Authored by: n8gray on Jul 05, '05 08:45:30PM

Uh, can somebody describe what PAC is, and what it might mean to turn it on or off?



[ Reply to This | # ]
10.4: Turn off PAC to avoid Safari performance problems
Authored by: Elander on Jul 06, '05 03:51:39AM

It's a file to automatically configure a proxy (PAC= Proxy Auto Configuration).

---

/elander



[ Reply to This | # ]
10.4: Turn off PAC to avoid Safari performance problems
Authored by: ynolo on Jul 06, '05 03:25:02PM

What's in a PAC?
A PAC file is a plain text file that, in its most basic form, consists of a single JScript® function called FindProxyForURL. Internet Explorer calls this function with two parameters: the full URL to which the user is navigating and the hostname portion of that URL. The FindProxyForURL function must return one of three possible strings: "DIRECT" tells Internet Explorer it should bypass the proxy server, "PROXY" followed by a proxy server name and port specifies a proxy, and "SOCKS" followed by a SOCKS server name and port specifies that Internet Explorer should use that SOCKS server. The auto-proxy file can also indicate some combination of these choices, delimited by semicolons.
The following PAC file will check whether the user is navigating to a page at www.harvest-books.org.
function FindProxyForURL(url,host)
{
if (host == "www.harvest-books.org")
return "DIRECT";

return "PROXY myproxy.harvest-books.org:80;
PROXY myotherproxy.harvest-
books.org:8080;
DIRECT" ;
}
If the user is going to the Harvest Books site, the function returns DIRECT, and Internet Explorer will bypass the proxy server for that address. If not, Internet Explorer will try to use myproxy.harvest-books.org on port 80. Notice that there are two proxy servers listed, separated by a semicolon; this is where the power of a PAC file starts to become apparent. If myproxy.harvest-books.org is down, unreachable, or otherwise not responding, Internet Explorer will try myotherproxy.harvest-books.org on port 8080, the next proxy server in the list. If neither proxy responds, Internet Explorer will bypass the proxy and attempt to connect directly (since the last item in the list is DIRECT). You can list any number of proxies for Internet Explorer to check, listed in order of preference.

More here:

http://www.microsoft.com/mind/0599/faq/faq0599.asp

---
i don\'t have one



[ Reply to This | # ]
10.4: Turn off PAC to avoid Safari performance problems
Authored by: RichB on Dec 15, '05 08:58:43PM

It's ironic that this great description of a PAC file is geared towards Internet Explorer which on the Mac has never been able to use a PAC file! Netscape and Mozilla products like Firefox always have been able to and with OS 10.3.8 Safari finally was able to as well by adding it to the bottom of the proxy choices. Tiger made it a separate pulldown menu for automatic versus manual entry. If you use a PAC file in Network System Preferences, IE on the Mac will not work!



[ Reply to This | # ]