Asking for a friend. Events in a small area like a small cave would be especially grand. E.g. destroying some skull in a cave spawns (event 1) a few waves of enemies (event 2) followed by a boss (event 3), something like that.
Edit: maybe I should've specified that I'm strictly looking within core content. No DLCs or expansions...
If its for the "do X events" weekly: the EoD map Dragons End, has a minidungeon called "Trial of the Elders". You need a Jade Bot Mastery to enter and it containes a total of 8 very fast events (they count as events but give no loot/xp), they can be done in a group or solo (recommend power reaper for solo play).
Not sure what level of content you're looking for and what reason, but I'll give it a go. The Heart of Thorns maps (apart from Dragon's Stand) all follow the "event chain" model. You can see the tower icons on the map to find where the event currently going is. After you complete a chain, there are normally a few more harder events afterwards. I'm not sure I'd consider them fast if the goal was just number of events. This is also true for the "mini zones" in the SotO maps.
There's an event in Thunderhead Peaks (in one of the puzzle rooms) to kill 1 elite that can be spammed over and over again (easy way to finish the Return To achievement)
Oh apologies! There are a lot of event chains all over the Orr maps (Southern Tyria). You can most likely run around those maps and constantly find events. The temple meats are chained events as well