Dear Maintainer,

The stable package version is very slow, likely due to missing fix
https://github.com/grosjo/fts-xapian/commit/6c1518ae8bf3cfc5993d1e653c53c5b9a206cb88
first introduced in 1.4.11.

See https://github.com/grosjo/fts-xapian/issues/89 "
grosjo commented on Jul 4, 2021

Yes, it seems the detection of the free memory was buggy, and the plugin
kept flushing on disk, which destroyed the performance
"

The stable backports 1.5.5-1~bpo11+1 version fixes this issue.

This bug report is there to point to a bug and tell the workaround
(install bullseye-backports version).
As this is not a security issue I doubt this commit would be added to
the bullseye version of the package.

stable version was indexing my 56G Maildir for more than a month with
1.4.9a-1+deb11u1 without even having half of it indexed.

Cheers,
Alban