Reset before the undead half
Razorfen Downs begins with quilboar and ends with undead. The undead half has a higher damage load and narrow corridors. Reset the pace before entering it.
Prepare for the gong
Single-pull the undead side. Corridor chains can begin when the second mob reaches the group.
Name the cleanser before that section: Shaman, Paladin, or Priest. Without one, slow the route and account for disease damage on every pull.
Before the gong: full health, full mana, and everyone stacked. Start only when the group is ready.
On Amnennar the Coldbringer, kill adds immediately and move out of the Frost Nova area.
Disease pressure
Diseases stack on the healer while they are watching the party. Cleanse them early. Starting the gong at 40% mana gives the skeleton waves an immediate advantage.
The gong needs a full reset
Use the gong after every player is ready and the party is stacked.