Mesh resolution will not affect noise levels. Bump (and normal) maps don't need SubD or high mesh densities as they don't displace the surface, they just change how light affects it.

TerraDome 3 does include an atmosphere effect - if that is loaded it will slow down the render engine, potentially by a great deal, which may mean your render is timing out before reaching the convergence level (which should not be set to 100% - better to leave it lower, if only a little, and adjust the quality setting).