Very nice looking. The ways that geometry would make a bike feel "less racy" would be if the wheelbase were very long or the trail were very long, stuff like that. The former isn't a problem for you, and I doubt the latter is either. The other thing that can cause a feeling of sluggishness would be too much flex robbing you of power. I generally discount the reality of that in modern frames and would highly doubt it is a factor in that bike. Especially since you describe it as stiff and harsh riding. If it were also power sucking, what would be the point of making such a frame. Could be larger tires. Try wheels and tires on it you are confident in if that is an option. Oh, and just like you have to check that the appliance is, in fact plugged in, when it isn't working, make sure your brakes aren't rubbing. Ya nevah know!