That's extremely suspicious. Geomipmapping, as all chunked LODs techniques can be extremely fast. When the required LOD is computed by quadtrees, I would expect it to go even faster (I used a linear scan).
so far i've used ROAM, Geomipmapping and of course Quadtrees, as well as a combination of the last two.
None of these were really optimal for what i'm trying to achieve, as in all cases they sucked up too many CPU resources (With geomipmapping being somewhat precomputed)
I'm somewhat inclined to say your program has an issue outside the LODding systems. Considering ROAM is totally dynamic in nature... you're not uploading the data each frame are you? How big is your average batch in unique vertices and how many batches are you sending? Do you have evidence the LODding algorithm itself is bottlenecking?