VirtualBox 6.x / Vagrant /data/wordpress mount very slow

[ottok]

This phenomenon was noticed today while looking into why the new Vagrant box with VirtualBox 6.x seems so sluggish:

Command that reads files in data mount is slow:

DEVELOPMENT [@wordpress:/data/wordpress] feature/wp-development-up(+5/-2)+* ± time git diff --shortstat
 22 files changed, 5 insertions(+), 2 deletions(-)

real    0m0.617s
user    0m0.029s
sys 0m0.148s

Same command in another dir outside of /data/wordpress is much faster, running in mere milliseconds.

This however does not happen on every vagrant up run. Some times the command runs faster:

DEVELOPMENT [@wordpress:/data/wordpress] feature/wp-development-up(+2/-2)+* ± time git diff --shortstat
 22 files changed, 2 insertions(+), 2 deletions(-)

real    0m0.080s
user    0m0.002s
sys 0m0.038s

I looked at mounts and network settings etc but did not discover anything special.