It could be really slow sometimes. I was thinking about trying to add a few lines to cudaMiner --benchmark mode so that it exits after autotune finds the best startup config and make a massive batch file with all the different kernels/lookup gaps/N factors and just let it play while I'm at work. Not sure if the GPU would like to jump up and down all day though.
This would be awesome!
An enhanced tuning mode that tries all possible warp configs with possible combinations of -H -C -L for a longer period to ensure accuracy and saves the data in a text file to review.