Illaoi late game is way too OP

So I just finished a game where we played a 5v4 (we had 5, they had 4) and both our mid and top fed both who was mid and who was top. I myself was fed by mid game and was munching champs pretty quickly... except for and : which makes sense.

However - while was very difficult to kill - was impossible. She successfully went 1v5 and killed us without losing more than half of her 7k+ health; not only that, her movement speed was almost double mine. The only times we killed her was when our 3 cc attacks all landed well timed and held her for 5-10 seconds collectively.

If she is going to be that powerful, with that much health and armor: she shouldn't be that fast.

For reference, I was with these items equipped: . We killed her once I added , and only barely - as I had stated. I went 19/10/8 and most of my deaths were from , which started once we were 5-10 minutes into mid game. I have posted the match history in a link, hopefully it works, otherwise I'll edit this post to include it.

I believe needs to be nerfed; at the very least her speed cut in half (or whatever will keep her slower than a fast ADC) for late game. This is my opinion and a possible solution; and hopefully you'll see where I'm coming from.

If you don't see where I'm coming from please let me know what I'm missing, it will hopefully give me perspective.

Edit: Just to be clear, my biggest issue isn't her health, armor, or damage (although that could be checked out): it's her speed. She is almost as fast as , which is ridiculous when you consider nothing equally fed can 1v1 or 2v1 her.