Dunno Xfrog Tune, but in XFrog 3.5, at the bottom of the interface, you have the poly count of the model visisble. You can use this to reduce the poly count of the model ( I don't remember exactly how, since I moved to XFrog 4 a long time ago, but if I remember right, it's a simple slider)
XFrog models can be poly heavy, and can take some time to load, but once loaded, I never had any problem using them in Vue.
I would recommend yopu export as lwo, less tweaking necessary in Vue (it saves the transmap, which 3ds doesn't do for example). You'll need to adjust bump values, they will come very strong in Vue, highlights, and the ambient/diffuse proportions in the effects tab of the material editor (you want 60% diffuse, 40% ambient).