diff --git a/quickjs.c b/quickjs.c
index 797dcfab7..4fb9f95b7 100644
--- a/quickjs.c
+++ b/quickjs.c
@@ -20017,29 +20017,36 @@ typedef struct JSFunctionDef {
     struct list_head child_list; /* list of JSFunctionDef.link */
     struct list_head link;
 
-    bool is_eval; /* true if eval code */
     int eval_type; /* only valid if is_eval = true */
-    bool is_global_var; /* true if variables are not defined locally:
+
+    /* Pack all boolean flags together as 1-bit fields to reduce struct size
+    while avoiding padding and compiler deoptimization. */
+    bool is_eval : 1; /* true if eval code */
+    bool is_global_var : 1; /* true if variables are not defined locally:
                            eval global, eval module or non strict eval */
-    bool is_func_expr; /* true if function expression */
-    bool has_home_object; /* true if the home object is available */
-    bool has_prototype; /* true if a prototype field is necessary */
-    bool has_simple_parameter_list;
-    bool has_parameter_expressions; /* if true, an argument scope is created */
-    bool has_use_strict; /* to reject directive in special cases */
-    bool has_eval_call; /* true if the function contains a call to eval() */
-    bool has_arguments_binding; /* true if the 'arguments' binding is
+    bool is_func_expr : 1; /* true if function expression */
+    bool has_home_object : 1; /* true if the home object is available */
+    bool has_prototype : 1; /* true if a prototype field is necessary */
+    bool has_simple_parameter_list : 1;
+    bool has_parameter_expressions : 1; /* if true, an argument scope is created */
+    bool has_use_strict : 1; /* to reject directive in special cases */
+    bool has_eval_call : 1; /* true if the function contains a call to eval() */
+    bool has_arguments_binding : 1; /* true if the 'arguments' binding is
                                    available in the function */
-    bool has_this_binding; /* true if the 'this' and new.target binding are
+    bool has_this_binding : 1; /* true if the 'this' and new.target binding are
                               available in the function */
-    bool new_target_allowed; /* true if the 'new.target' does not
+    bool new_target_allowed : 1; /* true if the 'new.target' does not
                                 throw a syntax error */
-    bool super_call_allowed; /* true if super() is allowed */
-    bool super_allowed; /* true if super. or super[] is allowed */
-    bool arguments_allowed; /* true if the 'arguments' identifier is allowed */
-    bool is_derived_class_constructor;
-    bool in_function_body;
-    bool backtrace_barrier;
+    bool super_call_allowed : 1; /* true if super() is allowed */
+    bool super_allowed : 1; /* true if super. or super[] is allowed */
+    bool arguments_allowed : 1; /* true if the 'arguments' identifier is allowed */
+    bool is_derived_class_constructor : 1;
+    bool in_function_body : 1;
+    bool backtrace_barrier : 1;
+    bool need_home_object : 1;
+    bool use_short_opcodes : 1; /* true if short opcodes are used in byte_code */
+    bool has_await : 1; /* true if await is used (used in module eval) */
+    
     JSFunctionKindEnum func_kind : 8;
     JSParseFunctionEnum func_type : 7;
     uint8_t is_strict_mode : 1;
@@ -20065,7 +20072,6 @@ typedef struct JSFunctionDef {
     int new_target_var_idx; /* variable containg the 'new.target' value, -1 if none */
     int this_active_func_var_idx; /* variable containg the 'this.active_func' value, -1 if none */
     int home_object_var_idx;
-    bool need_home_object;
 
     int scope_level;    /* index into fd->scopes if the current lexical scope */
     int scope_first;    /* index into vd->vars of first lexically scoped variable */
@@ -20081,7 +20087,6 @@ typedef struct JSFunctionDef {
 
     DynBuf byte_code;
     int last_opcode_pos; /* -1 if no last opcode */
-    bool use_short_opcodes; /* true if short opcodes are used in byte_code */
 
     LabelSlot *label_slots;
     int label_size; /* allocated size for label_slots[] */
@@ -20119,7 +20124,6 @@ typedef struct JSFunctionDef {
     int source_len;
 
     JSModuleDef *module; /* != NULL when parsing a module */
-    bool has_await; /* true if await is used (used in module eval) */
 } JSFunctionDef;
 
 typedef struct JSToken {