Heroes VII

I only have one question so far: does the AI take a very long time to make its moves in Heroes of Might and Magic VII for everyone else? I finally started the 4th mission as a Necromancer, and after playing for about 3-4 hours, I've only managed to progress 2-3 weeks because the mission starts with 500 gold and Adar-Malik at level 5. I'm wondering why I even bothered to level him up and Ludmila in the second mission if they lose their experience and spells in subsequent missions.