From 54dbdd14f96e13fce76d34883be46a9adff5c74f Mon Sep 17 00:00:00 2001
From: dvdvgt <40773635+dvdvgt@users.noreply.github.com>
Date: Fri, 20 Mar 2026 16:43:03 +0100
Subject: [PATCH 1/2] make thunking dynamically depended on call-depth

---
 .../effekt/generator/js/TransformerCps.scala  |  3 +--
 libraries/js/effekt_runtime.js                | 21 +++++++++++++++++++
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/effekt/shared/src/main/scala/effekt/generator/js/TransformerCps.scala b/effekt/shared/src/main/scala/effekt/generator/js/TransformerCps.scala
index 1d7ea09207..38049f3650 100644
--- a/effekt/shared/src/main/scala/effekt/generator/js/TransformerCps.scala
+++ b/effekt/shared/src/main/scala/effekt/generator/js/TransformerCps.scala
@@ -300,8 +300,7 @@ object TransformerCps extends Transformer {
     }
 
     case cps.Stmt.Jump(k, vargs, ks) =>
-      pure(js.Return(maybeThunking(js.Call(nameRef(k),
-        vargs.map(toJS) ++  List(toJS(ks)))))  :: Nil)
+      pure(List(js.Return(js.Call(js.Variable(js.JSName("THUNK_K")), nameRef(k) :: vargs.map(toJS) ++ List(toJS(ks))))))
 
 
     case cps.Stmt.App(Recursive(id, label, vparams, bparams, ks1, k1, used), vargs, bargs, MetaCont(ks), k) =>
diff --git a/libraries/js/effekt_runtime.js b/libraries/js/effekt_runtime.js
index bb149178db..65f98cd02f 100644
--- a/libraries/js/effekt_runtime.js
+++ b/libraries/js/effekt_runtime.js
@@ -135,6 +135,27 @@ function RESUME(cont, c, ks, k) {
   return () => c(meta, k1)
 }
 
+let _depth = 0
+
+function THUNK_K(k, v, ks) {
+  const threshold = 1000
+  if (_depth >= threshold) {
+    return () => k(v, ks)
+  } else {
+    _depth += 1
+    return k(v, ks)
+  }
+}
+
+function THUNK(prog) {
+  if (_depth >= threshold) {
+    return () => prog()
+  } else {
+    _depth += 1
+    return prog()
+  }
+}
+
 function RUN_TOPLEVEL(comp) {
   try {
     let a = comp(TOPLEVEL_KS, TOPLEVEL_K)

From a28d75664b39bd5f53e9bca3b25f79b7d12f49d1 Mon Sep 17 00:00:00 2001
From: dvdvgt <40773635+dvdvgt@users.noreply.github.com>
Date: Mon, 23 Mar 2026 16:32:14 +0100
Subject: [PATCH 2/2] tune threshold value

---
 libraries/js/effekt_runtime.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libraries/js/effekt_runtime.js b/libraries/js/effekt_runtime.js
index 65f98cd02f..ce9d965f72 100644
--- a/libraries/js/effekt_runtime.js
+++ b/libraries/js/effekt_runtime.js
@@ -138,7 +138,7 @@ function RESUME(cont, c, ks, k) {
 let _depth = 0
 
 function THUNK_K(k, v, ks) {
-  const threshold = 1000
+  const threshold = 512
   if (_depth >= threshold) {
     return () => k(v, ks)
   } else {