The bug

In the most recent snapshots, when you use the tick, or arbitrary_player_tick triggers, it will spam the console with "Loaded 'X' Advancements". This can cause quite a bit of lag, and it is next to impossible to find an error within this slew of messages.

To reproduce

1. Take the tick folder, down below, and drop it into the advancements folder of your world.
2. Open the world with the console open.
3. Observe lag, and lots of spam.