disgraciau: This happened me too with the retail version in my modern laptop. The only fix i found for this, are these two:

*Open a game that consume CPU resources (Crysis, Minecraft, etc.). The point is make the CPU work a bit hard. Then, minimize the game, open Blade, and play it. If you see that the speed is correct, minimize the game, and close the "CPU-eater game" that you have opened before.

*Download "Swords & More" mod. It's a mod that have lots of features, including an "speed adjuster". With this you'll be able to correct the roadrunner speed of the game with a couple of hotkeys. The problem of this mod is that it's "cheater", and makes the game easy unless you de-activate some options of this mod. Also, Mod Manager is required for make this working.

I would like to beg to GoG (without thanking them before the release of this masterpiece), that try to make a fix from the "Swords & More" mod that allows you modify the in-game speed for the people that we have this problem.

That's all. Thank you.

P.S: Sorry for my bad English.

disgraciau: Tried one more time, it keeps running fast as roadrunner to me. I need to have a game opened to make it working at normal speed.

I don't understand it, really, and even less when this issue is fixed.

Maybe something related with laptops or something? I don't know.