diff --git a/tests/bench/mut_rec_wf.lean b/tests/bench/mut_rec_wf.lean
new file mode 100644
index 0000000000..e834dad125
--- /dev/null
+++ b/tests/bench/mut_rec_wf.lean
@@ -0,0 +1,143 @@
+import Lean
+
+set_option Elab.async false
+
+open Lean Elab
+open Elab.Command (CommandElab CommandElabM elabCommand)
+open Parser.Command
+open Parser.Term
+
+-- Create a name.
+def strName (s : String) : Name := Name.anonymous |>.str s
+
+def mkIndStr (idx : Nat) : String := s!"S{idx}"
+def mkIndIdent (idx : Nat) : Ident := mkIdent <| strName <| mkIndStr idx
+
+def mkQualCtor (indIdx : Nat) (c : String) : Ident :=
+  mkIdent <| Name.anonymous |>.str (mkIndStr indIdx) |>.str c
+
+def mkBaseCtorStr (idx : Nat) : String := s!"base{idx}"
+def mkBaseCtorIdent (idx : Nat) : Ident := mkIdent <| strName <| mkBaseCtorStr idx
+
+def mkIndCtorStr (idx : Nat) : String := s!"ind{idx}"
+def mkIndCtorIdent (idx : Nat) := mkIdent <| strName <| mkIndCtorStr idx
+
+def mkFnIdent (idx : Nat) := mkIdent <| strName s!"f{idx}"
+
+def mkBaseCtor (dt : Ident) (cIdx : Nat): CommandElabM (TSyntax ``ctor) := do
+  let base := mkBaseCtorIdent cIdx
+  `(ctor| | $base:ident : $dt )
+
+/--
+`#test_gen name dt ccnt icnt` creates
+`dt` mutually inductive types where each type has `ccnt` nullary constructors
+and `icnt` unary recursive constructors
+-/
+syntax (name := testGen) (docComment)? "#test_gen" ident num num num : command -- declare the syntax
+
+@[command_elab testGen]
+def testGenImpl: CommandElab := fun stx => do
+  match stx with
+  | `(#test_gen $ns:ident $datatype_count $base_count $ind_count) =>
+    let datatype_count := datatype_count.getNat
+    let base_count := base_count.getNat
+    let ind_count := ind_count.getNat
+    let mkInd (dtIdx : Nat) : CommandElabM Command := do
+      let indName := mkIndIdent dtIdx
+      let dt := mkIndIdent dtIdx
+      -- Create constant case definitions
+      let baseCases ← Array.ofFnM (n := base_count) fun cIdx =>
+        let base := mkBaseCtorIdent cIdx
+        `(ctor| | $base:ident : $dt )
+      let indCases ← Array.ofFnM (n := ind_count) fun cIdx =>
+        let base := mkIndCtorIdent cIdx.val
+        let ind := mkIndIdent ((dtIdx + cIdx.val) % datatype_count)
+        `(ctor| | $base:ident : $ind -> $dt )
+      `(inductive $indName where
+        $baseCases:ctor*
+        $indCases:ctor*
+      )
+    let decls ← Array.ofFnM (n := datatype_count) fun i => mkInd i.val
+    elabCommand =<< `(
+      namespace $ns
+      mutual
+      $decls:command*
+      end
+      end $ns)
+    let mkRec (dtIdx : Nat) : CommandElabM Command := do
+      let recName := mkFnIdent dtIdx
+      let indName := mkIndIdent dtIdx
+      let baseCases ← Array.ofFnM (n := base_count) fun cIdx =>
+        let base := mkQualCtor dtIdx (mkBaseCtorStr cIdx.val)
+        `(matchAltExpr| | $base:ident => $base )
+      let indCases ← Array.ofFnM (n := ind_count) fun cIdx =>
+        let ctor := mkQualCtor dtIdx (mkIndCtorStr cIdx.val)
+        let fi :=   mkFnIdent ((dtIdx + cIdx.val) % datatype_count)
+        `(matchAltExpr| | $ctor:ident i => $ctor ($fi i))
+      if ind_count > 0 then
+        `(def $recName (x : $indName) : $indName :=
+            match x with
+            $baseCases:matchAlt*
+            $indCases:matchAlt*
+          termination_by sizeOf x
+        )
+      else
+        `(def $recName (x : $indName) : $indName :=
+            match x with
+            $baseCases:matchAlt*
+            $indCases:matchAlt*
+        )
+    let decls ← Array.ofFnM (n := datatype_count) fun i => mkRec i.val
+    elabCommand =<< `(
+      namespace $ns
+      mutual
+      $decls:command*
+      end
+      end $ns)
+
+  | _ =>
+    throwIllFormedSyntax
+
+
+-- set_option trace.profiler true
+-- set_option trace.profiler.threshold 5
+-- set_option trace.profiler.output "profiler.out"
+-- set_option trace.profiler.useHeartbeats true
+set_option profiler true
+-- set_option profiler.threshold 10
+-- set_option trace.Elab.definition.wf.eqns true
+-- set_option trace.Meta.Match.matchEqs true
+
+/-
+Expanding number of constants increases time quadraticly.
+#test_gen C 2 40 1
+#test_gen D 2 80 1
+-/
+
+-- Expanding number of indutive cases seems fairly quick until a typing point is reached.
+
+-- #test_gen A 1 1 4
+--#test_gen B 2 1 2
+--#test_gen C 2 1 4
+--#test_gen D 2 1 8
+--#test_gen E 2 1 16
+
+-- There is a big change with the change from 32 to 64.
+
+-- #test_gen F 2 1 32
+
+-- ..
+-- simp took 172ms
+-- process pre-definitions took 408ms
+--  elaboration took 268ms
+
+#test_gen G 2 1 64
+
+
+-- .. many more simp calls appearing than 32
+--  process pre-definitions took 1.97s
+--  elaboration took 5.47s
+
+-- On nightly-07-16, this triggers an internal error but it could not be reproduced on live (due to timeout).
+--   Lean.Environment:464:4: duplicate normalized declaration name H.f0 vs. H.f0
+--#test_gen H 2 1 128
diff --git a/tests/bench/speedcenter.exec.velcom.yaml b/tests/bench/speedcenter.exec.velcom.yaml
index ed27046d87..f284966839 100644
--- a/tests/bench/speedcenter.exec.velcom.yaml
+++ b/tests/bench/speedcenter.exec.velcom.yaml
@@ -427,6 +427,12 @@
   run_config:
     <<: *time
     cmd: lean simp_congr.lean
+- attributes:
+    description: mut_rec_wf
+    tags: [fast, suite]
+  run_config:
+    <<: *time
+    cmd: lean mut_rec_wf.lean
 - attributes:
     description: nat_repr
     tags: [fast, suite]