diff --git a/packages/react/src/ReactChildren.js b/packages/react/src/ReactChildren.js
index efb9a2a84b36f..3f74696c6be5a 100644
--- a/packages/react/src/ReactChildren.js
+++ b/packages/react/src/ReactChildren.js
@@ -28,17 +28,37 @@ const SUBSEPARATOR = ':';
  * @param {string} key to be escaped.
  * @return {string} the escaped key.
  */
-function escape(key) {
-  const escapeRegex = /[=:]/g;
-  const escaperLookup = {
-    '=': '=0',
-    ':': '=2',
-  };
-  const escapedString = ('' + key).replace(escapeRegex, function(match) {
-    return escaperLookup[match];
-  });
-
-  return '$' + escapedString;
+const escapeRegex = /[=:]/g;
+function escape(key: string): string {
+  const str = '' + key;
+
+  let escapeChar;
+  let result = '$';
+  let lastIndex = 0;
+
+  for (
+    let match = escapeRegex.exec(str);
+    match;
+    match = escapeRegex.exec(str)
+  ) {
+    switch (str.charCodeAt(match.index)) {
+      case 61: // =
+        escapeChar = '=0';
+        break;
+      case 58: // :
+        escapeChar = '=2';
+        break;
+      default:
+        continue;
+    }
+
+    if (lastIndex !== match.index) {
+      result += str.substring(lastIndex, match.index);
+    }
+    lastIndex = match.index + 1;
+    result += escapeChar;
+  }
+  return result + str.substring(lastIndex);
 }
 
 /**
diff --git a/packages/react/src/__tests__/ReactChildren-test.js b/packages/react/src/__tests__/ReactChildren-test.js
index 952807851c9b4..4c3dfbe689742 100644
--- a/packages/react/src/__tests__/ReactChildren-test.js
+++ b/packages/react/src/__tests__/ReactChildren-test.js
@@ -911,10 +911,20 @@ describe('ReactChildren', () => {
   it('should escape keys', () => {
     const zero = <div key="1" />;
     const one = <div key="1=::=2" />;
+    const two = <div key="=foo" />;
+    const three = <div key="foo=" />;
+    const four = <div key=":foo" />;
+    const five = <div key="foo:" />;
+    const six = <div key="foo" />;
     const instance = (
       <div>
         {zero}
         {one}
+        {two}
+        {three}
+        {four}
+        {five}
+        {six}
       </div>
     );
     const mappedChildren = React.Children.map(
@@ -924,6 +934,11 @@ describe('ReactChildren', () => {
     expect(mappedChildren).toEqual([
       <div key=".$1" />,
       <div key=".$1=0=2=2=02" />,
+      <div key=".$=0foo" />,
+      <div key=".$foo=0" />,
+      <div key=".$=2foo" />,
+      <div key=".$foo=2" />,
+      <div key=".$foo" />,
     ]);
   });
 
diff --git a/scripts/bench/yarn.lock b/scripts/bench/yarn.lock
index 93e1624cf6304..d8a2fe199093b 100644
--- a/scripts/bench/yarn.lock
+++ b/scripts/bench/yarn.lock
@@ -1231,11 +1231,7 @@ semver-diff@^2.0.0:
   dependencies:
     semver "^5.0.3"
 
-"semver@2 || 3 || 4 || 5", semver@^5.0.3, semver@^5.1.0, semver@^5.3.0:
-  version "5.4.1"
-  resolved "https://registry.yarnpkg.com/semver/-/semver-5.4.1.tgz#e059c09d8571f0540823733433505d3a2f00b18e"
-
-semver@~5.3.0:
+"semver@2 || 3 || 4 || 5", semver@^5.0.3, semver@^5.1.0, semver@^5.3.0, semver@~5.3.0:
   version "5.3.0"
   resolved "https://registry.yarnpkg.com/semver/-/semver-5.3.0.tgz#9b2ce5d3de02d17c6012ad326aa6b4d0cf54f94f"
 
diff --git a/scripts/rollup/results.json b/scripts/rollup/results.json
index eaded2bf89449..5a36a656e7270 100644
--- a/scripts/rollup/results.json
+++ b/scripts/rollup/results.json
@@ -1,52 +1,52 @@
 {
   "bundleSizes": {
     "react.development.js (UMD_DEV)": {
-      "size": 54827,
-      "gzip": 14889
+      "size": 55378,
+      "gzip": 15063
     },
     "react.production.min.js (UMD_PROD)": {
-      "size": 6638,
-      "gzip": 2814
+      "size": 6795,
+      "gzip": 2908
     },
     "react.development.js (NODE_DEV)": {
-      "size": 45243,
-      "gzip": 12588
+      "size": 45794,
+      "gzip": 12761
     },
     "react.production.min.js (NODE_PROD)": {
-      "size": 5433,
-      "gzip": 2366
+      "size": 5581,
+      "gzip": 2454
     },
     "React-dev.js (FB_DEV)": {
-      "size": 44587,
-      "gzip": 12097
+      "size": 45147,
+      "gzip": 12269
     },
     "React-prod.js (FB_PROD)": {
-      "size": 12883,
-      "gzip": 3454
+      "size": 13555,
+      "gzip": 3606
     },
     "react-dom.development.js (UMD_DEV)": {
-      "size": 574228,
-      "gzip": 133513
+      "size": 574390,
+      "gzip": 134564
     },
     "react-dom.production.min.js (UMD_PROD)": {
-      "size": 96421,
-      "gzip": 31352
+      "size": 96372,
+      "gzip": 31334
     },
     "react-dom.development.js (NODE_DEV)": {
-      "size": 555649,
-      "gzip": 129174
+      "size": 555811,
+      "gzip": 130187
     },
     "react-dom.production.min.js (NODE_PROD)": {
-      "size": 94318,
-      "gzip": 30178
+      "size": 94275,
+      "gzip": 30285
     },
     "ReactDOM-dev.js (FB_DEV)": {
-      "size": 573653,
-      "gzip": 131283
+      "size": 573827,
+      "gzip": 132455
     },
     "ReactDOM-prod.js (FB_PROD)": {
-      "size": 272535,
-      "gzip": 51556
+      "size": 272443,
+      "gzip": 51717
     },
     "react-dom-test-utils.development.js (NODE_DEV)": {
       "size": 36193,
@@ -117,64 +117,64 @@
       "gzip": 5914
     },
     "react-art.development.js (UMD_DEV)": {
-      "size": 361747,
-      "gzip": 80408
+      "size": 362006,
+      "gzip": 80510
     },
     "react-art.production.min.js (UMD_PROD)": {
       "size": 84292,
       "gzip": 26065
     },
     "react-art.development.js (NODE_DEV)": {
-      "size": 285834,
-      "gzip": 61333
+      "size": 286093,
+      "gzip": 61430
     },
     "react-art.production.min.js (NODE_PROD)": {
       "size": 47976,
       "gzip": 15085
     },
     "ReactART-dev.js (FB_DEV)": {
-      "size": 290183,
-      "gzip": 61074
+      "size": 290446,
+      "gzip": 61176
     },
     "ReactART-prod.js (FB_PROD)": {
       "size": 149114,
       "gzip": 25640
     },
     "ReactNativeRenderer-dev.js (RN_DEV)": {
-      "size": 415491,
-      "gzip": 91701
+      "size": 415754,
+      "gzip": 91798
     },
     "ReactNativeRenderer-prod.js (RN_PROD)": {
       "size": 201086,
       "gzip": 34724
     },
     "ReactRTRenderer-dev.js (RN_DEV)": {
-      "size": 290573,
-      "gzip": 61998
+      "size": 290836,
+      "gzip": 62091
     },
     "ReactRTRenderer-prod.js (RN_PROD)": {
       "size": 138274,
       "gzip": 23358
     },
     "ReactCSRenderer-dev.js (RN_DEV)": {
-      "size": 281173,
-      "gzip": 59079
+      "size": 281436,
+      "gzip": 59177
     },
     "ReactCSRenderer-prod.js (RN_PROD)": {
       "size": 130921,
       "gzip": 22026
     },
     "react-test-renderer.development.js (NODE_DEV)": {
-      "size": 282399,
-      "gzip": 60134
+      "size": 282658,
+      "gzip": 60233
     },
     "react-test-renderer.production.min.js (NODE_PROD)": {
       "size": 46329,
       "gzip": 14428
     },
     "ReactTestRenderer-dev.js (FB_DEV)": {
-      "size": 286844,
-      "gzip": 59878
+      "size": 287107,
+      "gzip": 59981
     },
     "react-test-renderer-shallow.development.js (NODE_DEV)": {
       "size": 10233,
@@ -193,8 +193,8 @@
       "gzip": 5097
     },
     "react-reconciler.development.js (NODE_DEV)": {
-      "size": 264252,
-      "gzip": 55746
+      "size": 264511,
+      "gzip": 55845
     },
     "react-reconciler.production.min.js (NODE_PROD)": {
       "size": 39641,