1 files changed, 25 insertions, 2 deletions

diff --git a/string.c b/string.c
index d931cd9ca..641018ab4 100644
--- a/string.c
+++ b/string.c
@@ -6915,9 +6915,32 @@ sym_call(VALUE args, VALUE sym, int argc, VALUE *argv)
 static VALUE
 sym_to_proc(VALUE sym)
 {
-    return rb_proc_new(sym_call, (VALUE)SYM2ID(sym));
-}
+    static VALUE sym_proc_cache = Qfalse;
+    enum {SYM_PROC_CACHE_SIZE = 67};
+    VALUE proc;
+    long id, index;
+    VALUE *aryp;
+
+    if (!sym_proc_cache) {
+        rb_gc_register_mark_object(sym_proc_cache);
+        sym_proc_cache = rb_ary_new2(SYM_PROC_CACHE_SIZE * 2);
+        rb_ary_store(sym_proc_cache, SYM_PROC_CACHE_SIZE*2 - 1, Qnil);
+    }
+
+    id = SYM2ID(sym);
+    index = (id % SYM_PROC_CACHE_SIZE) << 1;
 
+    aryp = RARRAY_PTR(sym_proc_cache);
+    if (aryp[index] == sym) {
+        return aryp[index + 1];
+    }
+    else {
+        proc = rb_proc_new(sym_call, (VALUE)id);
+        aryp[index] = sym;
+        aryp[index + 1] = proc;
+        return proc;
+    }
+}
 
 static VALUE
 sym_succ(VALUE sym)