Graph tool - computer config (GPU ~ OpenMP ~ CPU)

I ask myself what would be the better config to run graph tool easily with
large graphs (made from 5.10^5 square sparse correlation matrix with around
2/3 sparsity)

As far as I Know GPU dosn't suit to openMP. I conclue CPU multi threading is
the best option but maybe I am wrong ?

Graph-tool has no support for GPU off-loading, so the whole point is moot.