more low level optimizations
more low level optimizations

[git-p4: depot-paths = "//sw/gpgpu/nvbio/main/": change = 18036020]

NVlabs/nvbio,NVlabs/nvbio,kimrutherford/nvbio,kimrutherford/nvbio,NVlabs/nvbio,kimrutherford/nvbio,kimrutherford/nvbio,NVlabs/nvbio