Hi Stefan!

Sorry, I should have updated this thread.
So I never got around reproducing the issue with Gentoo, and soon after
I dropped Gentoo and moved to Guix, with which I've never been able to
re-experience this issue, even on massive Eshell buffers (couple of 10M...).

As far as I'm concerned, this could be closed, but maybe another Gentoo
user out there would be able to tell us more.

Cheers!

-- 
Pierre Neidhardt
https://ambrevar.xyz/