I'm noticing this on my server using the new-caves datapack in 21w16a. The lag spikes are consistent across certain chunk borders (as others have stated above) and take a few seconds each--enough to make the game practically unplayable. The only new information I have to add is that during each lag spike, the console fills with "Received invalid biome id: 1" warnings. In just a few minutes of play and a few border crossings, I have over 173,000 warnings of this type. Hope this helps.
Brady A
I'm noticing this on my server using the new-caves datapack in 21w16a. The lag spikes are consistent across certain chunk borders (as others have stated above) and take a few seconds each--enough to make the game practically unplayable. The only new information I have to add is that during each lag spike, the console fills with "Received invalid biome id: 1" warnings. In just a few minutes of play and a few border crossings, I have over 173,000 warnings of this type. Hope this helps.