Feat: script execution performance optimization

tests/forth/list_words.rs

@@ -2,7 +2,7 @@ use super::harness::*;
 
 #[test]
 fn choose_from_stack() {
-    let f = forth();
+    let mut f = forth();
     let ctx = default_ctx();
     f.evaluate("1 2 3 3 choose", &ctx).unwrap();
     let val = stack_int(&f);