Slow start of preview/render when directory is large

OP mentions in thread that the full directory subtree where the .qmd resides has 250k files.

Discussed in https://github.com/quarto-dev/quarto-cli/discussions/6751

^{Originally posted by mpauper September 7, 2023}

Description

I am rendering a single .qmd to html, and it is only using python and the jupyter engine. When I issue a render or preview command via CLI there is a 2-3 minutes delay until there is any stdout printed on the screen. Then follows the Starting python3 kernel...Done line which gets printed as is (there is no delay for the Done part).

Since there is nothing printed during the time before this gets printed, I am unsure how to interpret the delay. Is it still related to a slow start of the jupyter kernel?

I'd appreciate any pointers on what to check to figure this out!