This past Saturday, two friends and I played AoE II HD (Age of Empires II HD) online. We played a semi-custom scenario one of them had made with the three of us as a team in the middle of the map against 5 Hardest computers, high initial resources and starting in Post-Imperial age with a 10 minute Treaty (this is from the Forgotten Empires expansion pack).
One of the first things I noticed while trying to setup my markets was that the map was so huge and scrolling around wasn't getting me even to my neighboring ally's base, let alone to his marketplace. After we went back and forth with flares, we had our markets connected and we were getting our economies going.
Fast forward a half hour and my friend who ended up in the middle of the map had to go, so it was just two of us versus the 5 computers. We had just started attacks and I was noticing that my armies were getting to the enemy I was assigned to at weird times. I was making a mix of people to throw against him (Dark Blue) and my armies started out in formation and ended up in globs of people by the time they got to his wall.
Eventually, I make headway and we're fighting the computers, but it's slow going. It's the ludicrously-large map (Ludikris) and not only are my enemies taking forever to get there, but once they do, they make a small dent and I have to resupply them. I'm not helped by their lack of formation at the destination, so I build a new army-creating base (3-5 of each building) in Dark Blue's base and continue. After two hours of this, I remark to my friend that this is taking way too long. He's done slightly faster work of getting rid of his assigned computer, but not significantly faster.
When we finally get the last computer to resign, we realize it took over five and a half hours to wipe them out. We will never again play such a large map with so many resources, there's no chance of taking anyone out without a significant fight and we don't want to spend the entire night battling entrenched foes.
My recommendation: If you want to play the Ludikris map, start in a normal age so you have the normal 3 villager and 1 scout setup at the beginning. Then rush like crazy. If you spend a half hour or longer setting up, then your enemies (especially if they're any good/Hard/Hardest AI) will take at least an hour to destroy, each. Alternatively, you can play on that map with only 2 players and see who can grab the most land and take advantage of it.