Add a performance comment about the use of ecryptfs

diff --git a/performance.mdwn b/performance.mdwn
index b95868987d20c7e1aa5b377a0e8411ed4ec7985d..a6d7f2e84c465e6b384652c4a2aaa6e2b8655af6 100644 (file)
--- a/performance.mdwn
+++ b/performance.mdwn
@@ -3,6 +3,18 @@
 
 [[!toc levels=2]]
 
+## Use of ecryptfs slows notmuch down.
+
+I noticed that my `notmuch new` was really slow (several minutes) for
+less then 20 new emails (around 20K in my database).
+
+The performance tests in the notmuch source didn't show any real
+issue, even on a non-encrypted ext4 fs.
+
+After investigation and running different tests, a switch to a
+LUKS-btrfs based filesystem to replace the ext4-ecryptfs resolved the
+issue. It now takes some seconds to index hundreds of messages.
+
 ## Xapian 1.2.x database format: chert vs. flint
 
 Xapian 1.2 (in contrast to 1.0.x) uses a new database format called