Clearing the cache will not delete your stored passwords and login.
From your Safari menu bar click Safari > Preferences then select the Advanced tab.
Select: Show Develop menu in menu bar
Now click Develop from the menu bar. From the drop down menu click Empty Caches.
Quit and relaunch Safari. If you still have problems, try troubleshooting Safari extensions.
From the Safari menu bar click Safari > Preferences then select the Extensions tab. Turn that OFF, quit and relaunch Safari to test. I
If that helped, turn one extension on then quit and relaunch Safari to test until you find the incompatible extension then click uninstall.
I cleared the cache and turned off (even uninstalled) the one extension I had. I will say, that immediately zipped up Safari's performance in general. Many thanks!
Unfortunately, it did not solve the problem with Fedex.com which,
as I said, operates perfectly on Firefox.
This one's going to be a head-scratcher I think, but the overall speed improvement gained from your suggestions was certainly well worth it.
I've already informed Fedex.com, but they can not replicate the problem from their end using Firefox or Chrome.
Many thanks Carolyn!
Not sure I can be of much help in terms of a solution, but I will let you know that you are not alone. I'm runing OS X 10.7.5 and this happened to me as well. I use FedEx.com regularily and the slow down occured immediately after updating to Safari 6.1. I rebooted and it helped, but the site is still painful to use (when creating a new shipment). I have a feeling it has something to do with the AJAX code on the page. This happened once before a couple years ago. I don't remember the version of Safari or OS X or what fixed it .
Anyway, I'll post a solution if I find one. I think last time I just started using Firefox until a Safari update fixed the problem.