the mod01 aka usb2.0 mod enables faster loading of a game through the usb port providing you have hermies cios 202 installed(i think that's the usb2.0 ios one anyway)
as a direct result loading from a usb drive in my instance my external 1TB verbatim drive i get and added boost of performance(its not much in some cases but it makes a few game a bit more playable in terms of speed)
though because its unofficial there may be problems not in the official one(ive yet to see any though)
http://www.megaupload.com/?d=SY9EFE4N
that's the link to the usb2.0 mod provided on the compatibility list
if you download that you can ignore the wiisx folder in the root of the download as thats just the bios saves etc folder which you already have but if you open the apps folder in that download you can rename wiisx folder to something like wiisxusbmod or somthing similer and still keep the official wiisx beta 2 on your sd card
kinda like this
wiisxusbmod.zip extract
wiisxusbmod folder
apps- - - - wiisx- - - - rename this folder to wiisxusb
wiisx- - - - ignore that you already have it
at least you know if problems arise with the usb mod you can revert straight to the orriginal that way
oh and the xml file is already edited so on the HBC channel that wiisx will appear as usb 2.0 mod wiisx
oh and if that doesnt help performance try converting the .img to .bin an easy program to do this with is magiciso you can use the trial of it for free and it converts just fine