I created my first dimension in my single-player playthrough.

The dimension is lagging uncontrollably: Mobs lag, blocks lag, and I can’t even eat food.

More info please. Sneak right click with dimension tab in hand and show me that info

I merely created a randomly generated dimension.

The lag never ends. I can barely kill mobs and mine. The lag fully disappears when I exit the dimension.

What computer specs? Does it stay laggy if you wait? Did you try other dimensions?

I have a high-end computer. My FPS is high—this is lag, not frame rate issues. It stays laggy as long as I’m in the dimension. I haven’t tried other dimensions, but I’ll try it.

Thank you for taking the time to create this issue, as we're no longer supporting versions below 1.12, I'm going to go ahead and close it but if this bug seems to continue over to newer versions, please do report it again so we can investigate the issue further.