First step get a benchmark by going to
http://www.speedtest.net/ on both the PS3 browser and your PC browser.
Go Under the PS3 Internet Connection settings there is also a speed test. However it is not always the best way to get the most accurate results.
Now put your PS3 into the DMZ of your router.
Go to http://portforward.com/ it is the very best guide site and it is Free!
It has all the helpful info you are going to need to accomplish getting your PS3 into a DMZ on your router. it has router specific info and It even has a list of ports that need to be opened for this game.
To get started quick go here http://portforward.com/networking/st...ystation-3.htm
I found this video helped some as well,
In step #12 of the guide from portforward.com it mentions DNS servers.
Get your primary and secondary DNS server info here http://code.google.com/p/namebench/ .
Enter the DNS servers that are the two fastest on the list.
I am not saying this will fix your issues with this game or any other but it is a way to know that the issues are not on you end if you do these steps correctly.
Okay flamers flame away!