diff --git a/crates/oxide_vm/src/dispatch/call.rs b/crates/oxide_vm/src/dispatch/call.rs
index a3fe5bf6..477e087b 100644
--- a/crates/oxide_vm/src/dispatch/call.rs
+++ b/crates/oxide_vm/src/dispatch/call.rs
@@ -413,9 +413,12 @@ impl Vm {
                 }
             }
 
-            self.sub_module_stack.push(Arc::clone(&self.sub_modules));
             let callee_subs = &subs[sub_idx].sub_modules;
-            if !callee_subs.is_empty() {
+            if callee_subs.is_empty() {
+                self.sub_module_stack.push((Arc::clone(&self.sub_modules), None));
+            } else {
+                self.sub_module_stack
+                    .push((Arc::clone(&self.sub_modules), Some(std::mem::take(&mut self.immutables_cache))));
                 self.sub_modules = Arc::new(callee_subs.clone());
                 self.immutables_cache = (0..=callee_subs.len()).map(|_| OnceLock::new()).collect();
             }
diff --git a/crates/oxide_vm/src/vm.rs b/crates/oxide_vm/src/vm.rs
index 174c5624..7d6cf846 100644
--- a/crates/oxide_vm/src/vm.rs
+++ b/crates/oxide_vm/src/vm.rs
@@ -220,7 +220,7 @@ pub struct Vm {
     pub(crate) iters: IterState,
     /// 分组保存 inline cache 与指令计数器。
     pub(crate) profiling: ProfilingState,
-    pub(crate) sub_module_stack: Vec<Arc<Vec<CompiledModule>>>,
+    pub(crate) sub_module_stack: Vec<(Arc<Vec<CompiledModule>>, Option<Vec<OnceLock<Vec<JsValue>>>>)>,
     pub(crate) cell_stack: Vec<Vec<*mut Cell>>,
     pub(crate) temp_immutables: Vec<Vec<JsValue>>,
     /// 可复用字符串缓冲区，避免每次 `+` 拼接都分配。
@@ -811,10 +811,14 @@ impl Vm {
             }
         }
 
-        self.sub_module_stack.push(Arc::clone(&self.sub_modules));
         let callee_subs = &subs[sub_idx].sub_modules;
-        if !callee_subs.is_empty() {
+        if callee_subs.is_empty() {
+            self.sub_module_stack.push((Arc::clone(&self.sub_modules), None));
+        } else {
+            self.sub_module_stack
+                .push((Arc::clone(&self.sub_modules), Some(std::mem::take(&mut self.immutables_cache))));
             self.sub_modules = Arc::new(callee_subs.clone());
+            self.immutables_cache = (0..=callee_subs.len()).map(|_| OnceLock::new()).collect();
         }
 
         self.active_reg_limit = sub_n_registers.max(1);
diff --git a/crates/oxide_vm/src/vm_dispatch_misc.rs b/crates/oxide_vm/src/vm_dispatch_misc.rs
index c1f35593..b0310d25 100644
--- a/crates/oxide_vm/src/vm_dispatch_misc.rs
+++ b/crates/oxide_vm/src/vm_dispatch_misc.rs
@@ -143,6 +143,7 @@ impl Vm {
             self.bytecode = sub_bytecode;
             let subs = Arc::clone(&self.sub_modules);
             self.activate_immutables(sub_idx + 1, &subs[sub_idx].constants);
+            self.cell_stack.push(Vec::with_capacity(subs[sub_idx].cells_needed as usize));
 
             for (name, reg) in &self.sub_modules[sub_idx].builtin_reg_map {
                 let si = self.kernel_core.perm_interner().intern(name.as_str()).0;
diff --git a/crates/oxide_vm/src/vm_runtime.rs b/crates/oxide_vm/src/vm_runtime.rs
index 0d4c2266..d4652776 100644
--- a/crates/oxide_vm/src/vm_runtime.rs
+++ b/crates/oxide_vm/src/vm_runtime.rs
@@ -130,8 +130,11 @@ impl Vm {
         if let Some(saved_imm) = self.saved_immutables_stack.pop() {
             self.active_immutables = saved_imm;
         }
-        if let Some(saved_subs) = self.sub_module_stack.pop() {
+        if let Some((saved_subs, saved_cache)) = self.sub_module_stack.pop() {
             self.sub_modules = saved_subs;
+            if let Some(saved_cache) = saved_cache {
+                self.immutables_cache = saved_cache;
+            }
         }
         self.temp_immutables.pop();
         let offset = frame.saved_reg_offset as usize;
@@ -189,6 +192,7 @@ impl Vm {
         while let Some(handler) = self.try_stack.pop() {
             while self.frames.len() > handler.frame_depth {
                 if let Some(frame) = self.frames.pop() {
+                    self.cell_stack.pop();
                     self.restore_frame(frame);
                 }
             }
@@ -213,6 +217,7 @@ impl Vm {
         }
         self.close_for_of_above(0);
         while let Some(frame) = self.frames.pop() {
+            self.cell_stack.pop();
             self.restore_frame(frame);
         }
         let exc = self.exception_value.take().unwrap_or(JsValue::undefined());
diff --git a/crates/oxide_vm/src/vm_support.rs b/crates/oxide_vm/src/vm_support.rs
index 03ab9483..74be700a 100644
--- a/crates/oxide_vm/src/vm_support.rs
+++ b/crates/oxide_vm/src/vm_support.rs
@@ -211,6 +211,7 @@ impl Vm {
         self.regs = [JsValue::undefined(); 256];
         self.pc = 0;
         self.frames.clear();
+        self.sub_module_stack.clear();
         self.iters.reset();
         self.saved_bytecode_stack.clear();
         self.saved_immutables_stack.clear();