Most of it's really quick, the only tedious trash I found in the whole instance is the stuff before Horridon. Ji-kun trash is really quick if you don't step on unnecessary things and Megaera is really quick as well if you just go an efficient route prioritizing the bells.
I like trash that ties into boss abilities and that's what a lot of it tries to do prior to most of the bosses. The instance is large and it feels large, some of it's because of trash. Whats a boss if it doesn't have themed trash/minions prior to it? Oh, ToC.
There's a shit load of difficult trash (the ones before ji Kun for example) that dont give rep past friendly or drop gear.
Ji-Kun ones are the easiest trash, bet you say they are difficult because there is no groups of mobs there that you can AoE. I would say the trash on the bridges are hardest, mostly since those who have no clue just runs in and pulls multiple banshees.