I am rendering 20 sec. animation. It takes about 1 minute to render 1 frame. I left animation for rendering overnight. After 3-4 hours it slowed down. It took 12 hours to render 1 frame. Once I come back to check the render window this morning rendering went to normal speed (about 1 minute per frame). I have really simple scene set up. AO/Reflection channels in Texture applied to MoText.
Thank you for your help.