I've increased the speed by about 30%. It seemed like a good compromise between playability and looks.
Being one of the guys that weren't particularly happy with the movement speed of the characters ingame, i figured i'd give it a shot and see if i could mod it somewhat.
After messing around i eventually was successful. Took me a while to figure out that i needed to change the movement speed not for the player character objects but rather their root template.
So i increased their speed by about 30%. It seemed like a good compromise between playability and looks.
Keep in mind that this applies only to the 2 player characters. I'm not sure if it works for companions since i didn't get a chance to test it, but it can be improved pretty easily.
Just copy the content of the zip to your divinity game dir and make sure you activate the mod in the main menu. Also you'll probably have to start a new game.