Its not the size thats the problem since you use Riivo, it must have something to do with what your loading.
So what exacally are you using (not in terms of loader, but what you are loading in the first place)
I'm loading PAC files for almost every charictors for skins, have 1 stage PAC file that isn't completed so it freezes if u go on tht stage, and then the common5.PAC and that's it. Keep in mind everything loads perfect without the common5.PAC.