From ad1bd4481fb9ad69df8c07a0b38b46c0987f98e2 Mon Sep 17 00:00:00 2001
From: y-p <yoval@gmx.com>
Date: Thu, 21 Nov 2013 14:35:29 +0200
Subject: [PATCH] ENH: short-circuit config lookup when exact key given GH5147

---
 pandas/core/config.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/pandas/core/config.py b/pandas/core/config.py
index ac48232ec618f..bb591947d21de 100644
--- a/pandas/core/config.py
+++ b/pandas/core/config.py
@@ -512,6 +512,11 @@ def _select_options(pat):
     if pat=="all", returns all registered options
     """
 
+    # short-circuit for exact key
+    if pat in _registered_options:
+        return [pat]
+
+    # else look through all of them
     keys = sorted(_registered_options.keys())
     if pat == 'all':  # reserved key
         return keys