It works!!!

I finally resorted to installing the windows process monitor in order to see the file reads the process was doing, there I saw that a codec names Vodei was used every time one of the wave files played. This codec was part of the Vodei media player. I uninstalled the Vodei media player ...

Thanks for the quick response!!

Based on you suggestions I've done some testing, this is what I did:

Renamed the audio folder, this fixed the issue, but left me without audio of course.
Downloaded the audio folder with the mp3's and tried, no change, still freezes.

So I went for the quick ...

When I start to play the game the performance is rather bad, moving a unit might take several seconds before the game responds.
It doesn't happen with every move, but rather random every so often. It can also happen when I order a unit to attack.
The weird thing is that this behavior decreases ...