diff --git a/ExampleCodes/SpeedTest/fib.py b/ExampleCodes/SpeedTest/fib.py
index 88d9d7a..3f0ae16 100644
--- a/ExampleCodes/SpeedTest/fib.py
+++ b/ExampleCodes/SpeedTest/fib.py
@@ -1,11 +1,11 @@
 from time import time as tt
 
 def fib(x:int) -> int:
-    if x <= 1:  return x;
+    if x <= 1:  return x
     return fib(x-1) + fib(x-2)
 
 if __name__ == '__main__':
     t0 = tt()
-    result = fib(30)
+    result = fib(35)
     t1 = tt()
     print('cost: ',t1-t0, 'result:', result)
diff --git a/src/VM/VM.cpp b/src/VM/VM.cpp
index db33585..7a90205 100644
--- a/src/VM/VM.cpp
+++ b/src/VM/VM.cpp
@@ -209,8 +209,9 @@ namespace Fig
                 "none",
                 *currentFrame->proto->locations[ipIdx]));
         }
-        else
+        else [[likely]]
         {
+
             Object *obj = callee.AsObject();
             if (!obj->isFunction())
             {
diff --git a/xmake.lua b/xmake.lua
index 7928b5b..95b29d5 100644
--- a/xmake.lua
+++ b/xmake.lua
@@ -15,6 +15,10 @@ elseif is_plat("windows") then
     add_ldflags("-Wl,--stack,268435456")
 end
 
+if is_mode("release") then
+    set_optimize("fastest")
+end
+
 set_languages("c++23")
 add_includedirs("src")