Hi, I've had this problem for a few days and I don't know how to solve it.
For some reason, in my super flat world, with a few constructions, there is an incredible amount of MS, which makes it impossible for me to play. However, when I change the world (to anyone) everything works perfectly.
As you can see, the world is for testing (buildings most of the time), so if the file is corrupt I don't have much trouble erasing it, however, I'm afraid that it could happen in my survival world.
Everything I built in the world of evidence I rebuilt in survival, has nothing unusual.
I will list the things I have tried to solve the problem:
Reinstall Minecraft with backups of the worlds.
Get out of the world, lower the rendering distance to the minimum, restart Minecraft and enter the world.
Lower all other graphic options.
Run the option "optimize world".
Use an older version of the game (1.14.2 - 1.14 - 1.13.2) with backups in between.
Rise the amount of RAM the game can use. In this case I raised it to 6, more than that seems too much to me.
Increase the priority of the game in task manager.
Reload the chucks (several times).
There was not the slightest change with any option.
However, something strange happens: When I go into spectator mode, MS goes from 3000 to 20. For this reason I also tried to change my skin, I thought it was stupid and it didn't work.
The only thing that occurs to me is that the world is corrupt, I never opened the folder of it or had problems with the PC.
I have a Radeon RX550/500 series, 16GB of RAM, Intel(R) Core (TM) i7-8700 CPU and Windows 10.
English is not my main language, I'm sorry if there's any flaw.