Why did yarn become slow under WSL 2?

Question

Windows

I upgraded WSL to version 2 two weeks ago and yarn (serve | build) worked pretty fast in the beginning. Literally a couple of seconds to launch. A week has passed and after another reboot, yarn began to work terribly slowly. I didn’t do anything suspicious, I didn’t install anything, I didn’t configure anything.

"yarn serve" server now takes 40 to 80 seconds to start!
And, worse, stopped tracking file changes!

Yarn got a deep depression :(

Tried:

• reinstall Ubuntu 14.04
  
• uninstalled 14.04, installed Ubuntu 18.04
  
• run WSL from different consoles
  
• Googling but didn't find any similar issues.
  

What to do? Where to look?

Answer 1

This is a known situation . Disk performance dropped a lot in WSL2 when accessing files on the host filesystem, as From the point of view of WSL2, the host file system is a network one.
Detailed answer here .
TLDR: don't go to /mnt when you need performance, put the project's source code inside the WSL filesystem.