Interesting...I was having the same problem. I found the following.
Make sure you 'scroll' up when you land on the above url.
Here's what I did substituting OW for safari instructions:
Prep: Make sure OW is closed..not running, then proceed to...
Open OmniWeb's preferences file at ~/Library/Preferences/com.omnigroup.OmniWeb5.plist
MAKE A COPY AND SAVE ON DESKTOP.
Open 'com.omnigroup.OmniWeb5.plist' in a text editor. I use Text Wrangler
it's free :-)
Immediately below the first <dict> tag add the following two lines:
Close OW relaunch and see if Facebook loads faster.
If all is a mess, just use your copy to restore the original.
A couple of notes:
1. If after saving, your curious to see if you did it right, when you re-open the omnigroup.OmniWeb5.plist file you have to scroll all the way to the bottom where you'll see the above code that you entered. Again, all <key> entries are alphabetical.
2. If you have any doubts about doing this then don't do it. I'm living on a more desperate side. This was a first time to be messing around with the Preferences. I hope it works for you...my Facebook loaded fast. I'm using an Intel iMac with 3GBs of Ram...this little change with OW has made a difference for me.