Firewired multiple sony 810ul - preformance issues with laptop

Ill start with my set up - Im using a 2.26 pentium-m laptop with a full 2 gig of ram. I use nero 7 to burn, and I msconfig to turn off all other programs when I burn.I need to use external burners for my side job, wich is the editing and burning of dvds for weddings ect. (on site locations)
ok so I may have made a mistake here … I got a deal on the sony 810ul drives … and I use only 8x -r ty discs … I used to burn 2 discs on my desktop in 9 minutes (benq1640) but I need to do this on the road now so its not an option … I figured Id be able to daisy chain these and get a good proformance through my fire wire… I guess now that Ive found out that each one you add to the firewire slows down proformance? I went with 2 and the burns were 15 minutes … I figured since they were so much slower Id just get 2 more to save on the extra time … I picked up 2 more (4 total) and now its 30 minutes to do 4 through firewire. well thats just too long for the work I do when people are waiting … suggestions?
Would they run faster conected individually through usb maybe?
also … I was just thuinking are there slave/master settings on externals? Ill have to check that out too(Im at work right now)
Its not putting hardly any load on the laptop itself(maybe 25-40% cpu usage and about 20% ram usage …
I ran a disc check on my home computer and its add… Ive got constant pif, at 1 all along the dvd … ends up giving me a good overall score of 95-97%(qsuite benq)but Im sure it indicates a problem. Thank you for taking the time to read through all this, I just wanted to make sure all the info was out there. todd