diff --git a/docs/src/whatsnew/latest.rst b/docs/src/whatsnew/latest.rst
index 33f2e7a699..885be5d06e 100644
--- a/docs/src/whatsnew/latest.rst
+++ b/docs/src/whatsnew/latest.rst
@@ -117,6 +117,10 @@ This document explains the changes made to Iris for this release
    as well as some long-standing bugs with vertical coordinates and number
    formats. (:pull:`4411`)
 
+#. `@wjbenfold`_ resolved an issue that previously caused regridding with lazy
+   data to take significantly longer than with real data. Relevant benchmark
+   shows a time decrease from >10s to 625ms. (:issue:`4280`, :pull:`4400`)
+
 
 💣 Incompatible Changes
 =======================