Why it's the case that some games' (notably - Heroes of Might and Magic 5) AI actually speeds up when you use Cheat Engine's speed hack?

It’s a known issue that HoMM5’s AI is incredibly slow. Not only that – its pace slows down even more when the game progresses – so much that a number of excellent mods have been created to enchance it.

Recently, though, I learnt that I can use some popular, basic speed hacks (like the built-in one in Cheat Engine) to speed up the entire game – including the AI. While animation speed ups make sense (assuming they consist of keyframes and timepoints), I cannot wrap my head around how come speed-hacking makes the AI process faster.

I would like to know why is that and how exactly it’s affecting. I have solid background in C++, in general programming principles and a somewhat basic understanding of game engines. I do not have any solid background of any speed hacks, though.

I’m not quite sure whether this question fits the site, but my brief reserach on StackExchange network did not yield any better results that this one. I’ll be happy to be presented a more suitable place, if this one’s not appropriate.