Hello,
I don't have this problem on my Windows XP SP3 netbook. On my more powerful HP Pavilion 64 bit Windows 7 computer, Firefox portable version 12, which is located on the local NTFS hard drive (not on a USB drive), delays in the beginning of every connection at least 20 seconds. Then suddenly it loads the page normally. It looks like in the beginning of each connection attempt something prevents it from loading the page for a long time.
Running it as administrator or making all main and subfolders not read only did not solve this issue...
I run it without any extensions or modifications.
There is not any problem with Chrome on the same computer, so it is not a general connection issue.
Please help...