You can speedup DOSBox by setting the Core type to Dynamic and set Max Cycles. If you then also add a Frameskip of 2 or more, it will outperform vDos. Main advantage of DOSBox (for you) is that it can emulate many VGA+ resolutions so the image will be sharper. You could for instance try DOSBox SVN-Daum (http://ykhwong.x-y.net). Its menu allows to set/test different settings interactively.