diff --git a/include/mrbconf.h b/include/mrbconf.h
index 52bd17abf..869c24cc2 100644
--- a/include/mrbconf.h
+++ b/include/mrbconf.h
@@ -42,12 +42,6 @@
 #error Cannot define MRB_USE_FLOAT32 and MRB_NO_FLOAT at the same time
 #endif
 
-/* add -DMRB_NO_METHOD_CACHE to disable method cache to save memory */
-//#define MRB_NO_METHOD_CACHE
-/* size of the method cache (need to be the power of 2) */
-//#define MRB_METHOD_CACHE_SIZE (1<<8)
-//#define MRB_USE_INLINE_METHOD_CACHE
-
 /* define on big endian machines; used by MRB_NAN_BOXING, etc. */
 #ifndef MRB_ENDIAN_BIG
 # if (defined(BYTE_ORDER) && defined(BIG_ENDIAN) && BYTE_ORDER == BIG_ENDIAN) || \
diff --git a/src/class.c b/src/class.c
index 039fa29d9..bc73db358 100644
--- a/src/class.c
+++ b/src/class.c
@@ -50,11 +50,6 @@ typedef struct mt_tbl {
   union mt_ptr   *ptr;   /* block: [ ptr[0...alloc] | keys[0...alloc] ] */
 } mt_tbl;
 
-#ifdef MRB_USE_INLINE_METHOD_CACHE
-#define MT_INLINE_CACHE_SIZE 256
-static uint8_t mt_cache[MT_INLINE_CACHE_SIZE];
-#endif
-
 /* helper to get keys array */
 static inline mrb_sym*
 mt_keys(mt_tbl *t) {