diff --git a/CHANGES.md b/CHANGES.md
index a17734cfe35eefb16c01b85ee1d2a043bf82cd4d..7bd9d31619c4071c663b03797fec92701e4a7729 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,3 +1,10 @@
+# Synapse 1.91.1 (2023-09-04)
+
+### Bugfixes
+
+- Fix a performance regression introduced in Synapse 1.91.0 where event persistence would cause an excessive linear growth in CPU usage. ([\#16220](https://github.com/matrix-org/synapse/issues/16220))
+
+
 # Synapse 1.91.0 (2023-08-30)
 
 No significant changes since 1.91.0rc1.
diff --git a/debian/changelog b/debian/changelog
index 9c0f77e16a6026d7b726384779def4c5dc8eee42..f737041567e437ee6e3174fb1d0a435513c19819 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,9 @@
+matrix-synapse-py3 (1.91.1) stable; urgency=medium
+
+  * New Synapse release 1.91.1.
+
+ -- Synapse Packaging team <packages@matrix.org>  Mon, 04 Sep 2023 14:03:18 +0100
+
 matrix-synapse-py3 (1.91.0) stable; urgency=medium
 
   * New Synapse release 1.91.0.
diff --git a/pyproject.toml b/pyproject.toml
index c1f95e945847c3db636467a50ea1bb7207d2d192..4585584723e41cc72783ad1d90a526ca4f910892 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -89,7 +89,7 @@ manifest-path = "rust/Cargo.toml"
 
 [tool.poetry]
 name = "matrix-synapse"
-version = "1.91.0"
+version = "1.91.1"
 description = "Homeserver for the Matrix decentralised comms protocol"
 authors = ["Matrix.org Team and Contributors <packages@matrix.org>"]
 license = "Apache-2.0"