diff --git a/README.md b/README.md
index 7b5e864..7226cd3 100644
--- a/README.md
+++ b/README.md
@@ -214,3 +214,17 @@ aceiloz
 
 Puzzles that have only 10 answers worth more than 12 points must include
 multiple three-point answers.
+
+### Other puzzle variants
+
+Nothing requires the puzzle to have 7 available letters. If we only provide 6
+letters, we get fewer valid puzzles, but it takes less time to compute them.
+
+# letters | time | # puzzles
+
+--------------------------------------------------------------------------------
+
+3 | 20s | 0 4 | 2m20s | 189 5 | 10m29s | 6139 6 | 40m39s | 29105 7 | 180m41s |
+51912
+
+Times are using `-parallel=100` on a 12-core machine.