Tiger introduces a serious problem with proxy.pac, no fix is availablefrom Apple.
There is a serious flaw with using aproxy.pac URL for Safari 2.0 on Tiger (MacOS 10.4.1). Specifically, Safari loads the PAC file and parses it correctly forthe first HTTP request, and then repeats the process for each HTTP request it makes. So each new Tiger workstation vastly increases theload on the server hosting your PAC file.
So if a user visits http://www.cnn.com/ which contains 21 unique web objects,Safari will generate 21 additional requests for the PAC. This bug is easy to independently confirm by checking the access log on the server hosting the PAC file. I figured this out only after the PAC server crashed :)
