When looking at the Grim Dawn folder where save games are kept and finding the options file the setting "threads" was set to 1. I set it to 4 because the GPU is quad core. Now the game runs faster with about a 10 fps increase. Loading times are also cut by half. This may be old news but was so pleased with how much better the game is running I thought it would be of interest to some

Haven't tried this yet, but looking at that, use both options.
Better still, change the "2" to however many processor cores you have.