diff --git a/README.md b/README.md
index d45fd587e..6009b112f 100644
--- a/README.md
+++ b/README.md
@@ -63,6 +63,11 @@ unreleased features), read on.
        cd /path/to/the/swarm/repo
        cabal run -O0 swarm:exe:swarm
 
+   (Note that we recommend turning off optimizations with `-O0` since
+   they don't seem to make much difference to the speed of the
+   resulting executable, but they make a big difference in compilation
+   time.)
+
 1. Go get a snack while `cabal` downloads a Haskell compiler and
    all of Swarm's dependencies.