diff --git a/README.md b/README.md
index 2601f6ecf09cb6a2eca4b1422afd8ce5834ef078..712d27e46c35b6297be317f1cf4439f1b1c82eaf 100644
--- a/README.md
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@@ -64,3 +64,14 @@ eager exchanges are working and what effect the size of the packets has.
 
 ---------------------------
 Peter W. Draper 24 Sep 2019.
+
+Continuing from the notes above, there are also RDMA based versions of
+swiftmpistepsim, which are found in the various branches of the
+repository. That work and a re-working of SWIFT to use RDMA revealed that the
+main driver for the delays wasn't the scatter in MPI completion, but the time
+taken to copy data into and out of registered memory, the best solution to
+which was to make better use of the memory bandwidth by copying using multiple
+threads.
+
+-----------------------------
+Peter W. Draper 24 April 2023.