Unreasonably high ms ticks in 1.16.1 - severe delays in world interaction

I've been playing Minecraft today, and all of the sudden, I am experiencing unreasonably higher ms ticks in the world.

This has happened before during the 1.14 snapshots (see MC-138550) (but far worse), but it seems to make a comeback, unfortunately.

The Problems That Occur:

• Breaking a block in Survival will reappear for a few seconds before dropping
• Entities are much slower than usual, especially while attacking
• Eating will take a long time before it registers

What I Tried To Do:

• Lower Render Distance
• Lower Mipmap Levels
• Lower Entity Distance
• Decreased Particles
• Checked Random Tick Speed

What Ended Up Happening:

 - ms ticks remain between 50-150, where it should be way less...

Other Notes:

 Random Tick Speed is set to 3

 Seed: 732795237935697572

In the log, this seems to come up often:

[11:43:03] [Server thread/WARN]: Can't keep up! Is the server overloaded? Running [x]ms or [y] ticks behind

I have attached the world download for those who want to confirm. Please refer to the Environment tab of this issue to get the specs. If you have an old MacBook Air lying around, use it to test the issue.