Things I do that take experience to use properly but cut a lot (and I mean a LOT) of time:
- Automation of workers once key improvements are done and worker turns are less tight (in a game like this you steal so many just by attacking normally!). Early on turns are tight though so I had to micro them...especially on the earliest attack routes.
- In line with the above - using the governor button will affect what improvements workers make. You can actually specialize cities considerably with just automation. I know it isn't perfectly optimal, but I have patience limits, and with tons of workers it's not bad.
- City queuing and unit looping - this makes it so you don't have to get a popup, think about what to build every time, and figure out where that city was and what it was doing. Commerce cities get the commerce multipliers (and I pick the order but still order 5-6 buildings), production cities, on this map, get a forge, a barracks, a stable (using mounted), and them alt click on the unit to produce it indefinitely.
- Waypoints...A godsend. You don't have to touch units until they're all clumped somewhere. Eventually I was waging wars in 2 directions and waypointing troops to either side to save time.
On top of physical tools/tactics, there's a mental decision making process that varies from player to player. I'm on the fast end of the spectrum both here and in school, preferring not to delay decisions. Really though, on this type of format you want to win as fast as possible, and since I went the attack route the only decision was "who is it best to attack next?". Well, at first that would be civs without longbows. After everyone had those, I'd pick on nations that either couldn't make maces or knights yet, or were too small to mobilize meaningful resistance. Once I finally got some strong units myself (and tons of them!), I was able to steamroll the last civ or two and settle to fill in the cracks to nudge just barely over the threshold without having to take on the last 2 civs (master and vassal). Point is, a lot of decision making analysis can be done fast or slow too...and for each person their speed doing this depends on a lot of factors. If you do the above physical speed tips it should speed you up considerably though.